Ceramic materials and seals for high temperature reactive material devices

ABSTRACT

The disclosure provides seals for devices that operate at elevated temperatures and have reactive metal vapors, such as lithium, sodium or magnesium. In some examples, such devices include energy storage devices that may be used within an electrical power grid or as part of a standalone system. The energy storage devices may be charged from an electricity production source for later discharge, such as when there is a demand for electrical energy consumption.

CROSS-REFERENCE

This application is a continuation of U.S. application Ser. No.15/690,863, filed Aug. 30, 2017, now U.S. Pat. No. 10,637,015, which isa continuation of PCT Application Serial No. PCT/US2016/021048, filedMar. 4, 2016, which claims priority to U.S. Provisional Application No.62/128,838, filed Mar. 5, 2015, and U.S. Provisional Application No.62/208,518, filed Aug. 21, 2015, each of which is entirely incorporatedherein by reference.

BACKGROUND

Various devices are configured for use at elevated (or high)temperatures. Examples of such devices include elevated temperaturebatteries, which are devices capable of converting stored chemicalenergy into electrical energy. Batteries may be used in many householdand industrial applications. Another example of a high temperaturedevice is a chemical vapor deposition chamber such as those used in thefabrication of semiconductor devices. Another example of a hightemperature device is a chemical process vessel, a transfer pipe, orstorage vessel designed to process, transport, contain and/or storereactive metals. These devices typically may operate at a temperature ator in excess of 300° C.

SUMMARY

Recognized herein are various limitations associated with elevated (orhigh) temperature devices. For instance, some batteries operate at hightemperatures (e.g., at least about 100° C. or 300° C.) and have reactivematerial vapors (e.g., reactive metal vapors such as, for example,vapors of lithium, sodium, potassium, magnesium or calcium) that mayneed to be sufficiently contained within the devices. Other examples ofhigh temperature reactive material devices include nuclear (e.g., fusionand/or fission) reactors that use a molten salt or metal (e.g., moltensodium or lithium or molten sodium- or lithium-containing alloys) as acoolant, devices for manufacturing semiconductors, heterogeneousreactors, and devices for producing (e.g., processing) and/or handling(e.g., transporting or storing) reactive materials (e.g., reactivechemicals such as, for examples, a chemical with a strong chemicalreducing capability, or reactive metals such as, for example, lithium orsodium). Such devices may need to be sufficiently sealed from anexternal environment during use (e.g., to prevent device failure,prolong device use, or avoid adverse health effects on users oroperators of such devices), and/or may need a protective lining in thedevice to avoid corrosion of the container.

The present disclosure provides ceramic materials that may be used inhigh temperature devices and/or in other devices, including, forexample, strengthened ceramics used in ballistic protection systems anddevices (e.g., ballistic penetration resistant armor).

The present disclosure provides seals and/or reactor vessel linings forenergy storage devices and other devices having (e.g., containing orcomprising) reactive materials (e.g., reactive metals) and operating athigh temperatures (e.g., at least about 100° C. or 300° C.). The energystorage devices (e.g., batteries) may be used within an electrical powergrid or as part of a standalone system. The batteries may be chargedfrom an electricity production source for later discharge when there isa demand for electrical energy consumption.

An aspect of the present disclosure provides an electrochemical cellcomprising (a) a container comprising a reactive material maintained ata temperature of at least about 200° C.; and (b) a double seal thatseals the container from an environment external to the container. Thedouble seal comprises a first seal that is stable when in contact withthe reactive material and a second seal that is stable when in contactwith the external environment, such that (i) the first seal comprises asolid material that is not stable when in contact with the externalenvironment or (ii) the second seal comprises a solid material that isnot stable when in contact with the reactive material. In some cases,(i) the first seal comprises a solid material that is not stable when incontact with the external environment and (ii) the second seal comprisesa solid material that is not stable when in contact with the reactivematerial. The reactive material can comprise a reactive metal or vaporthereof. The reactive metal can be molten or liquid. The reactivematerial can comprise molten salt or a vapor thereof. The first seal canresist corrosion by molten lithium or a molten lithium salt. The secondseal can resist oxidation by air resulting in an increase in a leakagerate of the second seal. The first seal and the second seal can each behermetic. The first seal and the second seal can each provide a sealbetween the container and a conductor that protrudes through thecontainer through an aperture in the container. The first seal and thesecond seal can each comprise a ceramic component and a metal collaradjacent to the ceramic component. The double seal can comprise a sealarranged in a circumferential configuration, a seal arranged in astacked configuration, or a combination thereof. In some cases, theelectrochemical cell further comprises a pocket filled with inert gasbetween the first seal and the second seal. The double seal can surrounda conductor, a thermocouple or a voltage sensor coupled to thecontainer. The double seal can electrically isolate the conductor fromthe container.

Another aspect of the present disclosure provides a method to seal anelectrochemical cell comprising (a) providing a container comprising areactive material maintained at a temperature of at least about 200° C.;and (b) sealing the container with a double seal that seals thecontainer from an environment external to the container. The double sealcomprises a first seal that is stable when in contact with the reactivematerial and a second seal that is stable when in contact with theexternal environment, such that (i) the first seal comprises a solidmaterial that is not stable when in contact with the externalenvironment or (ii) the second seal comprises a solid material that isnot stable when in contact with the reactive material. The sealing cancomprise (i) sealing the first seal in an environment comprising a firstinert gas, thereby capturing the first inert gas inside the container;(ii) sealing the second seal, thereby forming a pocket between the firstseal and the second seal; (iii) filling the pocket with a second inertgas via a port; and (iv) sealing the port, thereby sealing the pocketand capturing the second inert gas in the pocket. The first or secondinert gas can comprise helium (He), or a mixture of argon (Ar) andhelium. The first or second inert gas can comprise between about 1% and5% He with balance Ar. The port can comprise a hole through a conductorthat protrudes through the container through an aperture in thecontainer, or a hole through a bushing between the first seal and thesecond seal. The sealing in (iv) can comprise closing the port via aweld.

Another aspect of the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; and (b) a seal inthe container that seals the container from an environment external tothe container. The seal comprises a ceramic component exposed to thereactive material and at least two metal sleeves joined to the ceramiccomponent. The seal is arranged in a stacked configuration withface-sealing interfaces that are substantially perpendicular to adirection parallel to a conductor that passes through the seal. At leastone of the face-sealing interfaces is configured as a concentricaccordion joint. The at least two metal sleeves are flexible, therebyallowing the seal to absorb at least a portion of internal thermalstresses during operation of the electrochemical cell. The seal can behermetic. The ceramic component can comprise aluminum nitride (AlN). Theat least two metal sleeves can comprise zirconium (Zr) or stainlesssteel. The temperature can be at least about 300° C. The seal can bemaintained at a temperature of least about 300° C. The seal can bestable when in contact with the reactive material and not stable when incontact with the external environment. In some cases, theelectrochemical cell further comprises additional ceramic componentsdistributed in a vertically symmetric configuration around the ceramiccomponent. In some cases, the electrochemical cell further comprises afirst coupler between the container and a first of the at least twometal sleeves. The first coupler can be flexible, thereby allowing theseal to absorb at least a portion of internal thermal stresses. In somecases, the electrochemical cell further comprises a second couplerbetween the conductor and a second of the at least two metal sleeves.The at least two metal sleeves, the first coupler and the second couplercan be configured with 30° slopes to allow for (i) self-fixturing of theseal during assembly at room temperature and/or (ii) when the seal is atits brazing temperature. The face-sealing interfaces can comprise 0.060″wide braze joints. The ceramic component can be chamfered. The at leasttwo metal sleeves and the first coupler can comprise angledself-fixturing features. The conductor can self-fixture with the secondcoupler.

Another aspect of the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; and (b) a seal inthe container that seals the container from an environment external tothe container. The seal comprises a ceramic component and at least twometal sleeves joined to the ceramic component. The seal is stable whenin contact with the external environment. The seal is not stable when incontact with the reactive material. The seal can be hermetic. Thetemperature can be at least about 300° C. The seal can be maintained ata temperature of least about 300° C. In some cases, the ceramiccomponent is not exposed to the reactive material. In some cases, theelectrochemical cell further comprises an additional seal that is stablewhen in contact with the reactive material nested within the seal. Theseal can be configured to bear a vertical load of at least about 10Newtons, thereby allowing at least a portion of the load to betransferred to the container as opposed to the additional seal. Theceramic component can comprise alumina. The at least two metal sleevescan comprise alloy 42. A coefficient of thermal expansion (CTE) of atleast one of the at least two metal sleeves can substantially match aCTE of the ceramic component, thereby reducing internal stresses withinthe ceramic component. The seal can have a height above a top plate ofthe container of less than about 2 inches, thereby reducing spacingbetween vertically stacked electrochemical cells. A conductor canprotrude through the container through an aperture in the container. Theseal can have an outer diameter of at least about 1 inch, or theaperture can be at least about 0.5 inches in diameter. A first of the atleast two metal sleeves can be joined to the ceramic component and theconductor via a braze joint with a braze length of less than about 0.080inches, thereby reducing thermal stresses at the braze joint.

Another aspect of the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; and (b) a seal inthe container that seals the container from an environment external tothe container. The seal comprises a ceramic component exposed to thereactive material and a metal sleeve joined to the ceramic component.The seal is arranged in a stacked configuration with one or more sealinginterfaces that are perpendicular to a direction parallel to a conductorthat passes through the seal. The ceramic component comprises aprotruding portion that substantially protrudes beyond at least one ofthe one or more sealing interfaces. The seal can be hermetic. Theceramic component can comprise aluminum nitride (AlN). The metal sleevecan comprise zirconium (Zr). The metal sleeve can be joined to thecontainer. The protruding portion can be adjacent to the conductor. Theprotruding portion can substantially protrude beyond a sealing interfaceon the ceramic component. The sealing interface on the ceramic componentcan comprise a braze joint. The protruding portion can have a thicknessthat substantially exceeds a thickness of the braze joint, therebyallowing the protruding portion to substantially protrude beyond thebraze joint. The ceramic component can increase or physically block anelectrical shorting path between the conductor and the metal sleeve. Theprotruding portion can further protrude downward from the seal in adirection parallel to the conductor to allow fixturing of the sealand/or the conductor. In some cases, the electrochemical cell furthercomprises an additional metal sleeve joined to the conductor. The metalsleeve can be joined to the container at a bottom surface of the ceramiccomponent and the additional metal sleeve can be joined to the conductorat a top surface of the ceramic component. The metal sleeves can bejoined to the ceramic component via braze joints with substantially thesame braze lengths, thereby reducing asymmetric forces on the seal. Theceramic component can comprise an inner diameter chamfer. Each of thebraze joints can be 0.080 inches wide and 0.002 inches thick. Adjacentsolid materials can have substantially matching coefficients of thermalexpansion, thus reducing potential for cracks forming within the ceramicupon brazing or cell operation. In some cases, the electrochemical cellfurther comprises additional ceramic components adjacent to the ceramiccomponent. The ceramic component can be positioned in the center of avertical stack of ceramic components. The seal can be stable when incontact with the reactive material. In some cases, the electrochemicalcell further comprises an additional seal that is stable when in contactwith the external environment and within which the seal is nested. Theceramic component can be compressed upon thermal expansion of theconductor, the container, the additional seal, or a combination thereof.

Another aspect of the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; and (b) a seal inthe container that seals the container from an environment external tothe container. The seal comprises a ceramic component exposed to thereactive material and a metal sleeve joined to the ceramic component.The seal is arranged in a stacked configuration with one or more sealinginterfaces that are perpendicular to a direction parallel to a conductorthat passes through the seal. An axially symmetric cross-section of theceramic component comprises at least two portions that are not parallelor perpendicular to each other. The ceramic component can besubstantially L-shaped. The ceramic component can comprise an innerdiameter chamfer. The reactive material can comprise an alkali metal oran alkaline earth metal. The reactive material can comprise magnesium(Mg), calcium (Ca), sodium (Na), potassium (K), lithium (Li), or anycombination thereof. The reactive material can further comprise one ormore of tin, lead, bismuth, antimony, tellurium, and selenium. Thereactive material further can comprise a Group 12 element. The ceramicmaterial can (i) be stable when in contact with lithium, (ii) be stablewhen in contact with air, (iii) have a coefficient of thermal expansion(CTE) substantially similar to a CTE of stainless steel, and (iv) beelectrically insulating. The ceramic material can comprise aluminumnitride (AlN), silicon nitride (Si₃N₄), magnesium oxide (MgO) orneodymium oxide (Nd₂O₃). The container and/or the conductor can comprise400-series steel, 300-series steel, nickel, titanium, zirconium, or anycombination thereof. In some cases, the electrochemical cell furthercomprises a sheath or liner between at least a portion of the reactivematerial and the container. The sheath or liner can comprise graphite.In some cases, the electrochemical cell further comprises a lining orcoating that covers an interior portion of the container. The lining orcoating can comprise an oxide material with a coefficient of thermalexpansion (CTE) substantially similar to a CTE of the container. The CTEof the oxide material can differ from the CTE of the container by lessthan about 20%. The oxide material can be stable when in contact withthe reactive material. The oxide material can comprise one or more ofneodymium oxide (Nd₂O₃), cerium oxide (CeO₂) and lanthanum oxide(La₂O₃), the container can comprise stainless steel, and the reactivematerial can comprise lithium.

Another aspect of the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; and (b) a seal inthe container that seals the container from an environment external tothe container. The seal comprises a ceramic component exposed to thereactive material and a metal sleeve joined to the ceramic component.The ceramic component comprises a lanthanide oxide. The ceramiccomponent comprises grains with a size of less than about 50 microns(μm). The lanthanide oxide can comprise neodymium oxide (Nd₂O₃). Theseal can further comprise a metallization layer bonded to the ceramiccomponent, wherein the ceramic component and the metallization layerform a pre-metallized ceramic component, wherein the metallization layercomprises greater than 50 at % niobium (Nb). In some cases, the ceramiccomponent further comprises less than or equal to about 10 weightpercent yttrium oxide (Y₂O₃). The ceramic component can further comprisegreater than or equal to about 5 weight percent silicon carbide (SiC).The metal sleeve can comprise alloy 52 or 18CrCb ferritic stainlesssteel. In some cases, the ceramic component further comprises greaterthan or equal to about 3 weight percent of a different oxide material.In some cases, the seal further comprises a first layer coated onto theceramic component, the first layer comprising yttrium (Y). The seal canfurther comprise a second layer coated onto the first layer, the secondlayer comprising chromium (Cr) or rhenium (Re). The ceramic component,the first layer and the second layer can form a pre-metallized ceramiccomponent. The seal can further comprise a third layer joining thepre-metallized ceramic component to the metal sleeve, the third layercomprising a nickel (Ni)-based material. The materials of the first,second and third layers can form at most one intermetallic compound witheach other. The first, second and third layers can form a layered brazebetween the ceramic component and the metal sleeve. In some cases, theseal further comprises a metallization powder bonded to the ceramiccomponent to form a first layer and a second layer on the ceramiccomponent. The ceramic component, the first layer and the second layercan form a pre-metallized ceramic component. At least one of the firstlayer and second layer can comprise a mutual reaction compound of themetallization powder and the ceramic component. The metallization powdercan comprise a metal powder mixed with a ceramic or glass material. Themetallization powder can comprise a metal selected from at least one ofmanganese (Mn) and molybdenum (Mo). The metallization powder cancomprise at least about 10% Mn, at least about 10%, 20%, 50%, or 70% Moand at least about 2% aluminum nitride (AlN). The first layer cancomprise a mutual reaction compound of the ceramic or glass material andthe ceramic component. The second layer can comprise the metal. Theceramic or glass material can comprise aluminum nitride (AlN), and themutual reaction compound can comprise Nd₂AlO₃N. The metallization powdercan be applied to the ceramic component as a slurry or paint. Themetallization powder can be melted at a temperature of greater than orequal to about 1330° C. The seal can further comprise a third layerjoining the pre-metallized ceramic component to the metal sleeve, thethird layer comprising nickel (Ni), copper (Cu) or a combinationthereof. The first, second and third layers can form a layered brazebetween the ceramic component and the metal sleeve. The container canfurther comprise a lining or coating comprising an oxide material thatcovers an interior portion of the container. The oxide material can bestable when in contact with the reactive material. The oxide materialcan comprise a lanthanide oxide. The container can further comprise amolten metal negative electrode that comprises at least a portion of thereactive material. At the temperature of the electrochemical cell, theceramic component can be stable (i) when in contact with the reactivematerial or (ii) when in contact with the external environment. At thetemperature of the electrochemical cell, the ceramic component can bestable (i) when in contact with the reactive material and (ii) when incontact with the external environment. The reactive material can belithium. The ceramic component can comprise grains with a size of lessthan about 10 μm. The metal sleeve can comprise stainless steel, and theceramic component can have a coefficient of thermal expansion that isless than about 10% different than a coefficient of thermal expansion ofthe metal sleeve. The metal sleeve can comprise a nickel alloy, and theceramic component can have a coefficient of thermal expansion that isless than about 10% different than a coefficient of thermal expansion ofthe metal sleeve. The metal sleeve can comprise at least about 40%nickel. The metal sleeve can comprise at least about 50% nickel. Themetal sleeve can comprise at least about 95% or 99% nickel. The seal cansurround a conductor that protrudes through the container through anaperture in the container.

Another aspect of the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; and (b) a seal inthe container that isolates the container from an environment externalto the container. The seal comprises a ceramic component exposed to thereactive material and a metal sleeve joined to the ceramic component.The ceramic component comprises a primary ceramic material and asecondary ceramic material. The primary ceramic material comprisesaluminum nitride (AlN). The secondary ceramic material increases astrength of the primary ceramic material by at least about 1%. Thesecondary ceramic material can comprise yttrium oxide (Y₂O₃), siliconcarbide (SiC), or a combination thereof. The secondary ceramic materialcan be included in the ceramic component in an amount that is greaterthan or equal to about 3 weight percent Y₂O₃, greater than or equal toabout 25 volume percent SiC, or a combination thereof. The secondaryceramic material can be included in the ceramic component in an amountthat is less than or equal to about 3 weight percent Y₂O₃, less than orequal to about 25 volume percent SiC, or a combination thereof. Thesecondary ceramic material can be included in the ceramic component inan amount that is less than about 5 or 3 weight percent Y₂O₃, greaterthan or equal to about 15 or 25 volume percent SiC, or a combinationthereof. The secondary ceramic material can be included in the ceramiccomponent in an amount that is greater than or equal to about 3 weightpercent Y₂O₃, less than about 25 volume percent SiC, or a combinationthereof. The seal can be stable when in contact with the reactivematerial. The metal sleeve can have a coefficient of thermal expansionthat is greater than or equal to about 10 microns per meter per degreeCelsius (μm/m/° C.). The ceramic component can comprise grains with asize of less than about 50 microns (μm). The primary ceramic materialand the secondary ceramic material can comprise grains with differentsizes. The seal can further comprise a metallization powder bonded tothe ceramic component to form a first layer and a second layer on theceramic component. The metallization powder can comprise a metal powderand a ceramic or glass material. The ceramic component, the first layerand the second layer can form a pre-metallized ceramic component. Themetallization powder can comprise a metal selected from at least one ofmanganese (Mn) and molybdenum (Mo). The metallization powder cancomprise at least about 10% Mn, at least about 10% Mo and at least about2% neodymium oxide (Nd₂O₃). The metallization powder can comprise atleast about 10% Mn, at least about 10% Mo and at least about 10%neodymium oxide (Nd₂O₃). The metallization powder can comprise at leastabout 10% Mn, at least about 10% Mo and at least about 20% neodymiumoxide (Nd₂O₃). The first layer can comprise a mutual reaction compoundof the ceramic or glass material and the ceramic component. The secondlayer can comprise the metal. The mutual reaction compound can compriseNd₂AlO₃N. The seal can further comprise a third layer joining thepre-metallized ceramic component to the metal sleeve, the third layercomprising nickel (Ni), copper (Cu) or a combination thereof. At least aportion of the third layer can comprise at least about 82% Ni. Thefirst, second and third layers can form a layered braze between theceramic component and the metal sleeve.

In another aspect, the present disclosure provides a ceramic materialcomprising at least about 30 weight percent (wt %) neodymium oxide(Nd₂O₃), wherein the ceramic material has a strength of greater than orequal to about 150 MPa.

In some embodiments, the ceramic material comprises at least about 40 wt% Nd₂O₃. In some embodiments, the ceramic material comprises at leastabout 50 wt % Nd₂O₃. In some embodiments, the ceramic material comprisesat least one of Nd₂O₃, ZrO₂ and Nd₂Zr₂O₇ crystal structures, and whereinthe ceramic material comprises less than or equal to about 38.7 atomicpercent (at %) Nd and 60.2 at % O, and greater than or equal to about1.1 at % Zr as measured on an atomic percentage basis.

In some embodiments, the ceramic material further comprises at least oneof SiC, TiC and Y₂O₃. In some embodiments, the ceramic material furthercomprises at least one of tetragonal zirconia polycrystal (TZP), ZrO₂,SiC, TiC and Y₂O₃. In some embodiments, at least a portion of theceramic material comprises grains with a size of less than about 50microns (μm). In some embodiments, a grain size of the SiC in theceramic material is less than about 1 μm. In some embodiments, theceramic material has a coefficient of thermal expansion (CTE) of betweenabout 8 ppm/K and 11 ppm/K for a temperature range of between about 20°C. and 500° C. In some embodiments, the ceramic material retainsmechanical strength after exposure to air at a temperature of at leastabout 400° C. for at least about 100 hours. In some embodiments, theceramic material retains mechanical strength after being submerged in areactive material at a temperature of at least about 400° C. for atleast about 8 hours. In some embodiments, the reactive materialcomprises lithium metal-saturated molten LiCl—LiBr—LiF salts. In someembodiments, the ceramic material retains mechanical strength afterbeing submerged in water at a temperature of at least about 25° C. forat least about 100 hours. In some embodiments, the ceramic materialfurther comprises greater than or equal to about 15 at % Nd, 1.5 at %Zr, 5.2 at % Ti and 5.2 at % C, and less than or equal to about 54.1 at% O. In some embodiments, the ceramic material further comprises greaterthan or equal to about 15 at % Nd, 2.5 at % Y, 2.3 at % Zr, 7.1 at % Siand 7.1 at % C, and less than or equal to about 51.9 at % O.

In some embodiments, the ceramic material has a strength greater than orequal to about 200 MPa. In some embodiments, the ceramic material has astrength greater than or equal to about 300 MPa. In some embodiments,the ceramic material functions as a dielectric insulator in a devicethat contains one or more reactive materials. In some embodiments, thedevice operates at a temperature of at least about 300° C. In someembodiments, the device is associated with a nuclear fission or fusionreactor. In some embodiments, the ceramic material functions as aprotective lining in a reactor chamber that contains reactive material.In some embodiments, the reactor chamber contains reactive material atan operating temperature of greater than about 300° C. In someembodiments, the reactive material is a reactive liquid metal. In someembodiments, the dielectric insulator is part of a gas-tight seal. Insome embodiments, the device is a liquid metal battery cell. In someembodiments, the liquid metal battery cell comprises molten lithiummetal and molten salts. In some embodiments, the liquid metal batterycell is operated at a temperature of at least about 300° C. In someembodiments, the seal comprises a ceramic-to-metal joint. In someembodiments, the ceramic-to-metal joint comprises a layered assemblythat includes the ceramic material, and a braze layer bonded to a metalsleeve. In some embodiments, the ceramic-to-metal joint furthercomprises a metallization layer bonded between the ceramic material andthe braze layer. In some embodiments, the metallization layer comprisesa primary metallization metal that includes niobium (Nb). In someembodiments, the metallization layer further comprises a secondarymetallization metal that includes Ti, Cr, Al, Mo or any combinationthereof. In some embodiments, the metallization layer comprises aceramic powder material comprising Nd₂O₃, AlN, Y₂O₃, TiO₂, Al₂O₃, CaO,SrO or any combination thereof. In some embodiments, the braze layercomprises a Ni-based braze alloy. In some embodiments, the braze layercomprises BNi-2, BNi-7 or BNi-5b braze alloy.

In some embodiments, the metal sleeve comprises 18CrCb ferriticstainless steel, 441 stainless steel, Inconel 600, ATI alloy 600 orHastelloy S. In some embodiments, the metal sleeve material has athickness of greater than or equal to about 75 μm.

Another aspect of the present disclosure provides a ceramic materialcomprising aluminum nitride (AlN); and at least one of silicon carbide(SiC) and titanium carbide (TiC), wherein at least a portion of the atleast one of SiC and TiC is in particle form other than whiskers. Theceramic material can have a grain size of less than about 50 microns(μm) and a porosity of less than about 1%.

In some embodiments, the ceramic material further comprises yttria(Y₂O₃), and wherein the ceramic material comprises about 3 weightpercent (wt %) Y₂O₃ and at least about 25 volume percent (vol %) SiC. Insome embodiments, the ceramic material has a tensile strength greaterthan about 400 MPa.

In some embodiments, a device for protecting against ballisticpenetration comprises the ceramic material. In some embodiments, thedevice is ballistic armor.

In some embodiments, a high temperature device containing reactivematerial(s) comprises a seal comprising the ceramic material.

In some embodiments, the ceramic material further comprises at leastabout 3 wt % Nd₂O₃. In some embodiments, the ceramic material furthercomprises at least about 5 wt % Nd₂AlNO₃. In some embodiments, theceramic material further comprises at least about 5 vol % SiC. In someembodiments, the ceramic material further comprises at least about 20vol % SiC. In some embodiments, the ceramic material has a tensilestrength of at least about 400 MPa.

In some embodiments, a device for holding reactive material(s) at anoperating temperature greater than about 300° C. comprises a sealcomprising the ceramic material.

In some embodiments, ballistic armor comprises the ceramic material.

In some embodiments, a grain size of the SiC in the ceramic material isless than or equal to about 1 μm. In some embodiments, the grain size ofthe SiC in the ceramic material is less than or equal to about 0.7 μm.In some embodiments, the grain size of the SiC in the ceramic materialis less than or equal to about 0.45 μm.

In some embodiments, the ceramic material comprises at least about 30weight percent (wt %) AlN. In some embodiments, the SiC is in particleform other than whiskers.

In some embodiments, the ceramic material further comprises greater thanor equal to about 20 at % Al, 20 at % N, 0.6 at % Y, 0.8 at % 0, 5.2 at% Si, and 5.2 at % C. In some embodiments, the ceramic material furthercomprises greater than or equal to about 20 at % Al, 20 at % N, 0.4 at %Nd, 0.6 at % 0, 5.2 at % Si, and 5.2 at % C. In some embodiments, theceramic material further comprises greater than or equal to about 20 at% Al, 20 at % N, 0.4 at % Nd, 0.6 at % 0, 1.8 at % Ti, and 1.8 at % C.In some embodiments, the ceramic material further comprises at leastabout 5 wt % TiC.

In another aspect, the present disclosure provides an electrochemicalcell comprising (a) a container comprising a reactive materialmaintained at a temperature of at least about 200° C.; (b) a seal in thecontainer that isolates the container from an environment external tothe container, the seal comprising a ceramic component exposed to thereactive material and a metal sleeve joined to the ceramic component;and (c) a coating on an external surface of the seal to protect themetal sleeve and/or the ceramic component from excessive oxidation, thecoating comprising phosphorus (P) and oxygen (O).

In some embodiments, the electrochemical cell further comprises aluminum(Al). In some embodiments, the coating comprises aluminophosphate glass.In some embodiments, the coating comprises Al—O—Al bonds. In someembodiments, the coating comprises nanometer scale carbon particles. Insome embodiments, the nanometer scale carbon particles are encapsulatedwithin the aluminophosphate glass. In some embodiments, the coatingcomprises phosphate glass. In some embodiments, the coating comprisesamorphous glass.

Additional aspects and advantages of the present disclosure will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein only illustrative embodiments of thepresent disclosure are shown and described. As will be realized, thepresent disclosure is capable of other and different embodiments, andits several details are capable of modifications in various obviousrespects, all without departing from the disclosure. Accordingly, thedrawings and description are to be regarded as illustrative in nature,and not as restrictive.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings (also “Figure” or “FIG.” herein), of which:

FIG. 1 is an illustration of an electrochemical cell (A) and acompilation (e.g., battery) of electrochemical cells (B and C);

FIG. 2 is a schematic cross-sectional illustration of a housing having aconductor in electrical communication with a current collector passthrough an aperture in the housing;

FIG. 3 is a cross-sectional side view of an electrochemical cell orbattery;

FIG. 4 is a cross-sectional side view of an electrochemical cell orbattery with an intermetallic layer;

FIG. 5 is a schematic cross-sectional illustration of an electrochemicalcell having feed-throughs that are electrically insulated from a housingwith dielectric seal components;

FIG. 6 shows examples of current collectors combined into a shared lidassembly (A and B);

FIG. 7 shows coefficients of thermal expansion in units of parts permillion (ppm) per ° C. for various types of steel and an insulatingceramic;

FIG. 8 shows the coefficient of thermal expansion in units of parts (p)per ° C. for various types of sleeve or collar materials, brazematerials and insulating ceramics;

FIG. 9 shows the Gibbs free energy of formation (ΔG_(r)) for variousmaterials at a range of temperatures with negative numbers being morethermodynamically stable;

FIG. 10 shows examples of features that can compensate for a coefficientof thermal expansion mismatch;

FIG. 11 shows an electrochemical cell having a brazed ceramic seal;

FIG. 12 shows a schematic drawing of a brazed ceramic seal where thematerials are thermodynamically stable with respect to the internal andexternal environments of the cell;

FIG. 13 shows a seal where the ceramic and/or braze materials are notthermodynamically stable with respect to the internal and externalenvironments;

FIG. 14 shows an example of a brazed ceramic seal;

FIG. 15 shows an example of a brazed ceramic seal;

FIG. 16 shows an example of a brazed ceramic seal;

FIG. 17 shows an example of a brazed ceramic seal;

FIG. 18 shows an example of a seal having an alumina or zirconia sealwith yttrium oxide (Y₂O₃) coating and iron-based braze;

FIG. 19 shows an example of a sub-assembly;

FIG. 20 shows how the shape of a sub-assembly can accommodatecoefficient of thermal expansion mismatch;

FIG. 21 shows a seal design having multiple ceramic insulators disposedbetween one or more metal sleeves;

FIG. 22 shows an example of the forces on a seal;

FIG. 23 shows a seal design having a single ceramic insulator disposedbetween one or more metal sleeves;

FIG. 24 shows a cell cap assembly;

FIG. 25 shows examples and features of seals;

FIG. 26 shows examples and features of seals;

FIG. 27 shows examples and features of seals;

FIG. 28 shows an example of a cell pack;

FIG. 29 shows an example of braze connection between the top of aconductive feed-through and the bottom of a cell;

FIG. 30 shows an example of joining two cells using a compressionconnection between parts that forms at the operating temperature of thebattery based on differences in the coefficient of thermal expansion;

FIG. 31 shows an example of a stack of cell packs, also referred to as acore;

FIG. 32 in an example of a method for selecting materials to form a sealbased on a rank-ordered free energy of formation selection process;

FIG. 33 is a cross-sectional view of an example of a double seal;

FIG. 34 is another example of a double seal;

FIG. 35 is a cross-section of a seal with a concentric accordion joint;

FIG. 36 is a cut-away view of another example of a seal with aconcentric accordion joint;

FIG. 37 is a cross-sectional view of an example of an air stable seal;

FIG. 38 is a sectioned side view of the seal in FIG. 37;

FIG. 39 shows cross-sectional views of a portion or component of a sealthat comprises a simple ceramic component and a portion or component ofa seal that comprises a shaped ceramic component.

FIG. 40 shows a cross-sectional view of an example of a seal with ashaped ceramic component; and

FIG. 41 is another example of the seal in FIG. 40.

DETAILED DESCRIPTION

While various embodiments of the invention have been shown and describedherein, it will be obvious to those skilled in the art that suchembodiments are provided by way of example only. Numerous variations,changes, and substitutions may occur to those skilled in the art withoutdeparting from the invention. It should be understood that variousalternatives to the embodiments of the invention described herein may beemployed. It shall be understood that different aspects of the inventioncan be appreciated individually, collectively, or in combination witheach other.

The term “direct metal-to-metal joining” or “direct metal-to-metaljoint,” as used herein, generally refers to an electrical connectionwhere two metal surfaces are brought into contact (e.g., by forming abraze or a weld). In some examples, direct metal-to-metal joints do notinclude wires.

The term “electronically,” as used herein, generally refers to asituation in which electrons can readily flow between two or morecomponents with little resistance. Components that are in electroniccommunication with one another can be in electrical communication withone another.

The term “vertical,” as used herein, generally refers to a directionthat is parallel to the force of gravity.

The term “stable,” as used herein to describe a material, generallyrefers to a material that is thermodynamically stable, chemicallystable, thermochemically stable, electrochemically stable, kineticallystable, or any combination thereof. A stable material may besubstantially thermodynamically, chemically, thermochemically,electrochemically and/or kinetically stable. A stable material may notbe substantially chemically or electrochemically reduced, attacked orcorroded. Any aspects of the disclosure described in relation to stable,thermodynamically stable or chemically stable materials may equallyapply to thermodynamically stable, chemically stable, thermochemicallystable and/or electrochemically stable materials at least in someconfigurations.

Ceramic Materials and Seals for High-Temperature Devices

The present disclosure provides a seal or a corrosion resistant liningfor a high-temperature device. The device can be a high temperaturereactive material device that contains/comprises one or more reactivematerials. For example, the high-temperature device can contain areactive material. In some cases, the device can be a high-temperaturereactive metal device. The device can be, without limitation, for theproduction and/or handling of a reactive material, such as, for example,a reactive metal (e.g., lithium, sodium, magnesium, aluminum, titaniumand/or other reactive metals) and/or a chemical with a strong chemicalreducing capability (e.g., reactive chemical), for semiconductormanufacturing, for a nuclear reactor (e.g., nuclear fusion/fissionreactor, nuclear reactor that uses a molten salt or metal, such as, forexample, molten sodium or lithium or molten sodium- orlithium-containing alloys, as a coolant), for a heterogeneous reactor,for a chemical processing device, for a chemical transportation device,for a chemical storage device, or for a battery (e.g., a liquid metalbattery). For instance, some batteries operate at high temperatures(e.g., at least about 100° C. or 300° C.) and have reactive metal vapors(e.g., lithium, sodium, potassium, magnesium, or calcium) that may needto be sufficiently contained within the battery. In some examples, suchhigh-temperature devices operate, are heated to and/or maintained at atemperature of at least about 100° C., 150° C., 200° C., 250° C., 300°C., 350° C., 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700°C., 750° C., 800° C., 850° C., 900° C. or more. At such temperatures,one or more components of the device can be in a liquid (or molten) orvaporized state.

The corrosion resistant lining may comprise a ceramic material. Theceramic material may function as a protective lining in a reactorchamber that contains reactive material. For example, the reactorchamber may contain reactive material at an operating temperature of,for example, greater than about 300° C. or 400° C. The reactive materialmay comprise or be a reactive liquid metal and/or molten salt(s). Insome cases (e.g., in some nuclear reactors), molten salt may be usedinstead of liquid metal. The molten salt may contain dissolved liquidreactive metal.

The ceramic material may function as a dielectric insulator in a devicethat contains one or more reactive materials. The device may operate ata temperature of, for example, at least about 300° C. or 400° C. Thedevice may be associated with a nuclear fission or fusion reactor. Thedielectric insulator may be part of a seal (e.g., a gas-tight seal). Theceramic material may be used in a seal of a device that containsreactive materials and operates at a temperature of greater than about300° C.

The seal can comprise a ceramic material (e.g., aluminum nitride (AlN))that is in contact with the reactive material (e.g., a reactive metal ormolten salt) contained in the device. The ceramic material can becapable of being chemically resistant to a reactive material (e.g., areactive material contained in the device, such as, for example,reactive metal or molten salt). The ceramic material can be capable ofbeing chemically resistant to the reactive material when the deviceoperates at a high temperature (e.g., at least about 100° C., 150° C.,200° C., 250° C., 300° C., 350° C., 400° C., 500° C., 600° C., 700° C.,800° C. or 900° C.).

The seal can comprise a metal collar or sleeve (e.g., made fromstainless steel (SS), zirconium, nickel, a nickel-based alloy or achromium-based alloy). A sleeve and/or the collar design can becoefficient of thermal expansion (CTE)-accommodating (e.g., canaccommodate differences in CTE (also “CTE mismatch” herein)). In somecases, a sleeve can be a collar. A collar can be conical. For example, acollar can be a conical metal (e.g., stainless steel) collar. Anyaspects of the disclosure described in relation to collars may equallyapply to sleeves at least in some configurations, and vice versa.

The seal can comprise an active metal braze disposed between the ceramicmaterial and at least one of the metal collar/sleeve and the device. Theactive metal braze can comprise a metal species that chemically reducesthe ceramic material (e.g., titanium (Ti) or zirconium (Zr)).

The seal can surround an electrically conductive feed-through (and canelectrically isolate the feed-through from a housing of the device), athermocouple or a voltage sensor. For example, the ceramic material canbe an insulator.

In some examples, the seal may be capable of being chemically resistantto reactive materials in the device at a temperature of at least about100° C., 150° C., 200° C., 250° C., 300° C., 350° C., 400° C., 500° C.,600° C., 700° C., 800° C. or 900° C. In some examples the seal may becapable of being chemically resistant to reactive materials at suchtemperatures for at least about 6 months, 1 year, 2 years, 5 years, 10years, 20 years or more. In some examples, the device can be ahigh-temperature reactive metal device, and the seal can be capable ofbeing chemically resistant to materials in the device that comprise thereactive metal. In an example, the seal is capable of being resistant tolithium vapor at a temperature of at least about 300° C. for at leastabout one year. The seal can retain the reactive material (e.g., vaporsof the reactive material) in the device. For example, the seal canretain reactive metal vapors and/or molten salt vapors in the device.

Electrochemical Cells, Devices and Systems

The present disclosure provides electrochemical energy storage devices(e.g., batteries) and systems. An energy storage device may form or beprovided within an energy storage system. The electrochemical energystorage device generally includes at least one electrochemical cell,also “cell” and “battery cell” herein, sealed (e.g., hermeticallysealed) within a housing. A cell can be configured to deliver electricalenergy (e.g., electrons under potential) to a load, such as, forexample, an electronic device, another energy storage device or a powergrid.

An electrochemical cell of the disclosure can include a negativeelectrode, an electrolyte adjacent to the negative electrode, and apositive electrode adjacent to the electrolyte. The negative electrodecan be separated from the positive electrode by the electrolyte. Thenegative electrode can be an anode during discharge. The positiveelectrode can be a cathode during discharge. A cell can include anegative electrode of material ‘A’ and a positive electrode of material‘B’, denoted as A∥B. The positive and negative electrodes can beseparated by an electrolyte. A cell can also include a housing, one ormore current collectors, and a seal (e.g., a high temperatureelectrically isolating seal).

In some examples, an electrochemical cell is a liquid metal batterycell. In some examples, a liquid metal battery cell can include a liquidelectrolyte arranged between a negative liquid (e.g., molten) metalelectrode and a positive liquid (e.g., molten) metal, metalloid and/ornon-metal electrode. In some cases, a liquid metal battery cell has amolten alkaline earth metal (e.g., magnesium, calcium) or alkali metal(e.g., lithium, sodium, potassium) negative electrode, an electrolyte,and a molten metal positive electrode. The molten metal positiveelectrode can include, for example, one or more of tin, lead, bismuth,antimony, tellurium and selenium. For example, the positive electrodecan include Pb, a Pb—Sb alloy or Bi. The positive electrode can alsoinclude one or more transition metals or d-block elements (e.g., Zn, Cd,Hg) alone or in combination with other metals, metalloids or non-metals,such as, for example, a Zn—Sn alloy or Cd—Sn alloy. In some examples,the positive electrode can comprise a metal or metalloid that has onlyone stable oxidation state (e.g., a metal with a single or singularoxidation state). Any description of a metal or molten metal positiveelectrode, or a positive electrode, herein may refer to an electrodeincluding one or more of a metal, a metalloid and a non-metal. Thepositive electrode may contain one or more of the listed examples ofmaterials. In an example, the molten metal positive electrode caninclude lead and antimony. In some examples, the molten metal positiveelectrode may include an alkali or alkaline earth metal alloyed in thepositive electrode.

In some examples, an electrochemical energy storage device includes aliquid metal negative electrode, a liquid metal positive electrode, anda liquid salt electrolyte separating the liquid metal negative electrodeand the liquid metal positive electrode. The negative electrode caninclude an alkali or alkaline earth metal, such as lithium, sodium,potassium, rubidium, cesium, magnesium, barium, calcium, sodium, orcombinations thereof. The positive electrode can include elementsselected from transition metals, d-block elements (e.g., Group 12) orGroup IIIA, IVA, VA and VIA of the periodic table of the elements (e.g.,zinc, cadmium, mercury, aluminum, gallium, indium, silicon, germanium,tin and lead), pnicogens (e.g., arsenic, bismuth and antimony),chalcogens (e.g., sulfur, tellurium and selenium), or any combinationthereof. In some examples, the positive electrode comprises a Group 12element of the periodic table of the elements, such as one or more ofzinc (Zn), cadmium (Cd) and mercury (Hg). In some cases, the positiveelectrode may form a eutectic or off-eutectic mixture (e.g., enablinglower operating temperature of the cell in some cases). In someexamples, the positive electrode comprises a first positive electrodespecies and a second positive electrode species at a ratio (mol-%) ofabout 20:80, 40:60, 50:50, 60:40, or 80:20 of the first positiveelectrode species to the second electrode species. In some examples, thepositive electrode comprises Sb and Pb at a ratio (mol-%) of about20:80, 40:60, 50:50, 60:40, or 80:20 Sb to Pb. In some examples, thepositive electrode comprises between about 20 mol-% and 80 mol-% of afirst positive electrode species mixed with a second positive electrodespecies. In some cases, the positive electrode comprises between about20 mol-% and 80 mol-% Sb (e.g., mixed with Pb). In some cases, thepositive electrode comprises between about 20 mol-% and 80 mol-% Pb(e.g., mixed with Sb). In some examples, the positive electrodecomprises one or more of Zn, Cd, Hg, or such material(s) in combinationwith other metals, metalloids or non-metals, such as, for example, aZn—Sn alloy, Zn—Sn alloy, Cd—Sn alloy, Zn—Pb alloy, Zn—Sb alloy, or Bi.In an example, the positive electrode can comprise about 15:85, 50:50,75:25 or 85:15 mol-% Zn:Sn.

The electrolyte can include a salt (e.g., molten salt), such as analkali or alkaline earth metal salt. The alkali or alkaline earth metalsalt can be a halide, such as a fluoride, chloride, bromide, or iodideof the active alkali or alkaline earth metal, or combinations thereof.In an example, the electrolyte (e.g., in Type 1 or Type 2 chemistries)includes lithium chloride. In some examples, the electrolyte cancomprise sodium fluoride (NaF), sodium chloride (NaCl), sodium bromide(NaBr), sodium iodide (NaI), lithium fluoride (LiF), lithium chloride(LiCl), lithium bromide (LiBr), lithium iodide (LiI), potassium fluoride(KF), potassium chloride (KCl), potassium bromide (KBr), potassiumiodide (KI), calcium fluoride (CaF₂), calcium chloride (CaCl₂), calciumbromide (CaBr₂), calcium iodide (CaI₂), or any combination thereof. Inanother example, the electrolyte includes magnesium chloride (MgCl₂). Asan alternative, the salt of the active alkali metal can be, for example,a non-chloride halide, bistriflimide, fluorosulfano-amine, perchlorate,hexaflourophosphate, tetrafluoroborate, carbonate, hydroxide, nitrate,nitrite, sulfate, sulfite, or combinations thereof. In some cases, theelectrolyte can comprise a mixture of salts (e.g., 25:55:20 mol-%LiF:LiCl:LiBr, 50:37:14 mol-% LiCl:LiF:LiBr, 34:32.5:33.5 mol-%LiCl—LiBr—KBr, etc.). The electrolyte may exhibit low (e.g., minimal)electronic conductance. For example, the electrolyte can have anelectronic transference number (i.e., percentage of electrical(electronic and ionic) charge that is due to the transfer of electrons)of less than or equal to about 0.03% or 0.3%.

In some cases, the negative electrode and the positive electrode of anelectrochemical energy storage device are in the liquid state at anoperating temperature of the energy storage device. To maintain theelectrodes in the liquid states, the battery cell may be heated to anysuitable temperature. In some examples, the battery cell is heated toand/or maintained at a temperature of about 100° C., 150° C., 200° C.,250° C., 300° C., 350° C., 400° C., 450° C., 475° C., 500° C., 550° C.,600° C., 650° C. or about 700° C. The battery cell may be heated toand/or maintained at a temperature of at least about 100° C., 150° C.,200° C., 250° C., 300° C., 350° C., 400° C., 450° C., 475° C., 500° C.,550° C., 600° C., 650° C., 700° C., 800° C. or 900° C. In such a case,the negative electrode, electrolyte and positive electrode can be in aliquid (or molten) state. In some situations, the battery cell is heatedto between about 200° C. and 600° C., 500° C. and 550° C. or 450° C. and575° C.

In some implementations, the electrochemical cell or energy storagedevice may be at least partially or fully self-heated. For example, abattery may be sufficiently insulated, charged, discharged and/orconditioned at sufficient rates, and/or cycled a sufficient percentageof the time to allow the system to generate sufficient heat throughinefficiencies of the cycling operation that cells are maintained at agiven operating temperature (e.g., a cell operating temperature abovethe freezing point of at least one of the liquid components) without theneed for additional energy to be supplied to the system to maintain theoperating temperature.

Electrochemical cells of the disclosure may be adapted to cycle betweencharged (or energy storage) modes and discharged modes. In someexamples, an electrochemical cell can be fully charged, partiallycharged or partially discharged, or fully discharged.

In some implementations, during a charging mode of an electrochemicalenergy storage device, electrical current received from an externalpower source (e.g., a generator or an electrical grid) may cause metalatoms in the metal positive electrode to release one or more electrons,dissolving into the electrolyte as a positively charged ion (i.e.,cation). Simultaneously, cations of the same species can migrate throughthe electrolyte and may accept electrons at the negative electrode,causing the cations to transition to a neutral metal species, therebyadding to the mass of the negative electrode. The removal of the activemetal species from the positive electrode and the addition of the activemetal to the negative electrode stores electrochemical energy. In somecases, the removal of a metal from the positive electrode and theaddition of its cation to the electrolyte can store electrochemicalenergy. In some cases, electrochemical energy can be stored through acombination of removal of the active metal species from the positiveelectrode and its addition to the negative electrode, and the removal ofone or more metals (e.g., different metals) from the positive electrodeand their addition to the electrolyte (e.g., as cations). During anenergy discharge mode, an electrical load is coupled to the electrodesand the previously added metal species in the negative electrode can bereleased from the metal negative electrode, pass through the electrolyteas ions, and deposit as a neutral species in the positive electrode (andin some cases alloy with the positive electrode material), with the flowof ions accompanied by the external and matching flow of electronsthrough the external circuit/load. In some cases, one or more cations ofpositive electrode material previously released into the electrolyte candeposit as neutral species in the positive electrode (and in some casesalloy with the positive electrode material), with the flow of ionsaccompanied by the external and matching flow of electrons through theexternal circuit/load. This electrochemically facilitated metal alloyingreaction discharges the previously stored electrochemical energy to theelectrical load.

In a charged state, the negative electrode can include negativeelectrode material and the positive electrode can include positiveelectrode material. During discharging (e.g., when the battery iscoupled to a load), the negative electrode material yields one or moreelectrons, and cations of the negative electrode material. In someimplementations, the cations migrate through the electrolyte to thepositive electrode material and react with the positive electrodematerial (e.g., to form an alloy). In some implementations, ions of thepositive metal species (e.g., cations of the positive electrodematerial) accept electrons at the positive electrode and deposit as ametal on the positive electrode. During charging, in someimplementations, the alloy at the positive electrode disassociates toyield cations of the negative electrode material, which migrate throughthe electrolyte to the negative electrode. In some implementations, oneor more metal species at the positive electrode disassociates to yieldcations of the negative electrode material in the electrolyte. In someexamples, ions can migrate through an electrolyte from an anode to acathode, or vice versa. In some cases, ions can migrate through anelectrolyte in a push-pop fashion in which an entering ion of one typeejects an ion of the same type from the electrolyte. For example, duringdischarge, an alkali metal anode and an alkali metal chlorideelectrolyte can contribute an alkali metal cation to a cathode by aprocess in which an alkali metal cation formed at the anode interactswith the electrolyte to eject an alkali metal cation from theelectrolyte into the cathode. The alkali metal cation formed at theanode in such a case may not necessarily migrate through the electrolyteto the cathode. The cation can be formed at an interface between theanode and the electrolyte, and accepted at an interface of the cathodeand the electrolyte.

Cells may have voltages. Charge cutoff voltage (CCV) may refer to thevoltage at which a cell is fully or substantially fully charged, such asa voltage cutoff limit used in a battery when cycled in a constantcurrent mode. Open circuit voltage (OCV) may refer to the voltage of acell (e.g., fully or partially charged) when it is disconnected from anycircuit or external load (i.e., when no current is flowing through thecell). Voltage or cell voltage, as used herein, may refer to the voltageof a cell (e.g., at any state of charge or charging/dischargingcondition). In some cases, voltage or cell voltage may be the opencircuit voltage. In some cases, the voltage or cell voltage can be thevoltage during charging or during discharging. Voltages of the presentdisclosure may be taken or represented with respect to referencevoltages, such as ground (0 volt (V)), or the voltage of the oppositeelectrode in an electrochemical cell.

The present disclosure provides Type 1 and Type 2 cells, which can varybased on, and be defined by, the composition of the active components(e.g., negative electrode, electrolyte and positive electrode), andbased on the mode of operation of the cells (e.g., low voltage modeversus high voltage mode). A cell can comprise materials that areconfigured for use in Type 2 mode of operation. A cell can comprisematerials that are configured for use in Type 1 mode of operation. Insome cases, a cell can be operated in both a high voltage (Type 2)operating mode and the low voltage (Type 1) operating mode. For example,a cell with positive and negative electrode materials that areordinarily configured for use in a Type 1 mode can be operated in a Type2 mode of operation. A cell can be cycled between Type 1 and Type 2modes of operation. A cell can be initially charged (or discharged)under Type 1 mode to a given voltage (e.g., 0.5 V to 1 V), andsubsequently charged (then discharged) under Type 2 mode to a highervoltage (e.g., 1.5 V to 2.5 V, or 1.5 V to 3 V). In some cases, cellsoperated under Type 2 mode can operate at a voltage between electrodesthat can exceed those of cells operated under Type 1 mode. In somecases, Type 2 cell chemistries can operate at a voltage betweenelectrodes that can exceed those of Type 1 cell chemistries operatedunder Type 1 mode. Type 2 cells can be operated in Type 2 mode.

In an example Type 1 cell, upon discharging, cations formed at thenegative electrode can migrate into the electrolyte. Concurrently, theelectrolyte can provide a cation of the same species (e.g., the cationof the negative electrode material) to the positive electrode, which canreduce from a cation to a neutrally charged metallic species, and alloywith the positive electrode. In a discharged state, the negativeelectrode can be depleted (e.g., partially or fully) of the negativeelectrode material (e.g., Li, Na, K, Mg, Ca). During charging, the alloyat the positive electrode can disassociate to yield cations of thenegative electrode material (e.g., Li⁺, Na⁺, Mg²⁺, Ca²⁺), which migratesinto the electrolyte. The electrolyte can then provide cations (e.g.,the cation of the negative electrode material) to the negativeelectrode, where the cations accept one or more electrons from anexternal circuit and are converted back to a neutral metal species,which replenishes the negative electrode to provide a cell in a chargedstate. A Type 1 cell can operate in a push-pop fashion, in which theentry of a cation into the electrolyte results in the discharge of thesame cation from the electrolyte.

In an example Type 2 cell, in a discharged state the electrolytecomprises cations of the negative electrode material (e.g., Li⁺, Na⁺,Mg²⁺, Ca²⁺), and the positive electrode comprises positive electrodematerial (e.g., Sb, Pb, Sn, Zn, Hg). During charging, a cation of thenegative electrode material from the electrolyte accepts one or moreelectrons (e.g., from a negative current collector) to form the negativeelectrode comprising the negative electrode material. In some examples,the negative electrode material is liquid and wets into a foam (orporous) structure of the negative current collector. In some examples,negative current collector may not comprise foam (or porous) structure.In some examples, the negative current collector may comprise a metal,such as, for example, tungsten (e.g., to avoid corrosion from Zn),tungsten carbide or molybdenum negative collector not comprising Fe—Nifoam. Concurrently, positive electrode material from the positiveelectrode sheds electrons (e.g., to a positive current collector) anddissolves into the electrolyte as cations of the positive electrodematerial (e.g., Sb³⁺, Pb²⁺, Sn²⁺, Zn²⁺, Hg²⁺). The concentration of thecations of the positive electrode material can vary in verticalproximity within the electrolyte (e.g., as a function of distance abovethe positive electrode material) based on the atomic weight anddiffusion dynamics of the cation material in the electrolyte. In someexamples, the cations of the positive electrode material areconcentrated in the electrolyte near the positive electrode.

In some implementations, negative electrode material may not need to beprovided at the time of assembly of a cell that can be operated in aType 2 mode. For example, a Li∥Pb cell or an energy storage devicecomprising such cell(s) can be assembled in a discharged state havingonly a Li salt electrolyte and a Pb or Pb alloy (e.g., Pb—Sb) positiveelectrode (i.e., Li metal may not be required during assembly).

Although electrochemical cells of the present disclosure have beendescribed, in some examples, as operating in a Type 1 mode or Type 2mode, other modes of operation are possible. Type 1 mode and Type 2 modeare provided as examples and are not intended to limit the various modesof operation of electrochemical cells disclosed herein.

In some cases, an electrochemical cell comprises a liquid metal negativeelectrode (e.g., sodium (Na) or lithium (Li)), a liquid (e.g.,LiF—LiCl—LiBr, LiCl—KCl or LiCl—LiBr—KBr) or solid ion-conductingelectrolyte (e.g., β″-alumina ceramic), and a liquid or semi-solidpositive electrode (e.g., a solid matrix or particle bed impregnatedwith a liquid or molten electrolyte). Such a cell can be a hightemperature battery. One or more such cells can be provided in anelectrochemical energy storage device. The negative electrode maycomprise an alkali or alkaline earth metal, such as, for example,lithium, sodium, potassium, magnesium, calcium, or any combinationthereof. The positive electrode and/or electrolyte may comprise a liquidchalcogen or a molten chalcogen-halogen compound (e.g., elemental, ionicor other form of sulfur (S), selenium (Se) or tellurium (Te)), a moltensalt comprising a transition metal halide (e.g., halides comprising Ni,Fe, Cr, Mn, Co or V, such as, for example, NiCl₃ or FeCl₃), a solidtransition metal (e.g., particles of Ni, Fe, Cr, Mn, Co or V), sulfur,one or more metal sulfides (e.g., FeS₂, FeS, NiS₂, CoS₂, or anycombination thereof), a liquid or molten alkali halometallate (e.g.,comprising Al, Zn or Sn) and/or other (e.g., supporting) compounds(e.g., NaCl, NaF, NaBr, NaI, KCl, LiCl or other alkali halides, bromidesalts, elemental zinc, zinc-chalcogen or zinc-halogen compounds, ormetallic main-group metals or oxygen scavengers such as, for example,aluminum or transition metal-aluminum alloys), or any combinationthereof. The solid ion-conducting electrolyte may comprise a betaalumina (e.g., β″-alumina) ceramic capable of conducting sodium ions atelevated or high temperature. In some instances, the solidion-conducting electrolyte operates above about 100° C., 150° C., 200°C., 250° C., 300° C. or 350° C.

Any aspects of the disclosure described in relation to cathodes canequally apply to anodes at least in some configurations. Similarly, oneor more battery electrodes and/or the electrolyte may not be liquid inalternative configurations. In an example, the electrolyte can be apolymer, a gel or a paste. In a further example, at least one batteryelectrode can be a solid, a gel or a paste. Furthermore, in someexamples, the electrodes and/or electrolyte may not include metal.Aspects of the disclosure are applicable to a variety of energystorage/transformation devices without being limited to liquid metalbatteries.

Batteries and Housings

Electrochemical cells of the disclosure can include housings that may besuited for various uses and operations. A housing can include one cellor a plurality of cells. A housing can be configured to electricallycouple the electrodes to a switch, which can be connected to theexternal power source and the electrical load. The cell housing mayinclude, for example, an electrically conductive container that iselectrically coupled to a first pole of the switch and/or another cellhousing, and an electrically conductive container lid that iselectrically coupled to a second pole of the switch and/or another cellhousing. The cell can be arranged within a cavity of the container. Afirst one of the electrodes of the cell (e.g., positive electrode) cancontact and be electrically coupled with an endwall of the container. Asecond one of the electrodes of the cell (e.g., negative electrode) cancontact and be electrically coupled with a conductive feed-through orconductor (e.g., negative current lead) on the container lid(collectively referred to herein as “cell lid assembly,” “lid assembly”or “cap assembly” herein). An electrically insulating seal (e.g., bondedceramic ring) may electrically isolate negative potential portions ofthe cell from positive portions of the container (e.g., electricallyinsulate the negative current lead from the positive current lead). Inan example, the negative current lead and the container lid (e.g., cellcap) can be electrically isolated from each other, where a dielectricsealant material can be placed between the negative current lead and thecell cap. As an alternative, a housing includes an electricallyinsulating sheath (e.g., alumina sheath) or corrosion resistant andelectrically conductive sheath or crucible (e.g., graphite sheath orcrucible). In some cases, a housing and/or container may be a batteryhousing and/or container.

A cell can have any cell and seal configuration disclosed herein. Forinstance, the active cell materials can be held within a sealedsteel/stainless steel container with a high temperature seal on the celllid. A negative current lead can pass through the cell lid (and besealed to the cell lid by the dielectric high temperature seal), andconnect with a porous negative current collector (e.g., metal foam)suspended in an electrolyte. In some cases, the cell can use a graphitesheath, coating, crucible, surface treatment or lining (or anycombination thereof) on the inner wall of the cell crucible (e.g.,container). In other cases, the cell may not use a graphite sheath,coating, crucible, surface treatment or lining on an inner wall of thecell crucible (e.g., container).

During cell operation, material (e.g., Fe) from a wall of the cell canreact under the higher voltage potential (e.g., Type 2 mode), and ionizeas a soluble species in the electrolyte. Hence, the wall material candissolve into the electrolyte and subsequently interfere with the cell'selectrochemistry. For example, the dissolved material can deposit on thenegative electrode, which, in some cases, can grow as dendrites andstretch across the electrolyte to one or more walls of the cell, ortoward the positive electrode, which can result in a short failure. Thepresent disclosure provides various approaches for suppressing orotherwise helping minimize the dissolution of solid (passive) cellmaterial such as Fe and its potentially negative effects on cellperformance by, for example, formation of dendrites and cell shorting.In some cases, a cell can be designed such that increased spacingbetween the negative electrode and a wall of the cell suppresses orotherwise helps minimize the ability of dendrites from forming andshorting the wall to the inner wall. A cell can include an electricallyinsulating, and chemically stable sheath or coating between one or morewalls of the cell and the negative electrode, electrolyte and/orpositive electrode to minimize or prevent shorting to the one or morewalls of the cell. In some cases, the cell can be formed of anon-ferrous container or container lining, such as a carbon-containingmaterial (e.g., graphite), or a carbide (e.g., SiC, TiC), or a nitride(e.g., TiN, BN), or a chemically stable metal (e.g., Ti, Ni, B). Thecontainer or container lining material may be electrically conductive.Such non-limiting approaches can be used separately or in combination,for suppressing or otherwise helping minimize chemical interactions withFe or other cell wall materials, and any subsequent negative effects oncell performance.

A cell may have a set of dimensions. In some cases, a cell can begreater than or equal to about 4 inches wide, 4 inches deep and 2.5inches tall. In some cases, a cell can be greater than or equal to about8 inches wide, 8 inches deep and 2.5 inches tall. In some examples, anygiven dimension (e.g., height, width or depth) of an electrochemicalcell can be at least about 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7,7.5, 8, 8.5, 9, 9.5, 10, 12, 14, 16, 18 or 20 inches. In an example, acell (e.g., each cell) can have dimensions of greater than or equal toabout 4 inches×4 inches×2.5 inches. In another example, a cell (e.g.,each cell) can have dimensions of greater than or equal to about 8inches×8 inches×2.5 inches. In some cases, a cell may have greater thanor equal to about 50 Watt-hours of energy storage capacity. In somecases, a cell may have at least about 200 Watt-hours of energy storagecapacity.

One or more electrochemical cells (“cells”) may be arranged in groups.Examples of groups of electrochemical cells include modules, packs,cores, CEs and systems.

A module can comprise cells that are attached together in parallel by,for example, mechanically connecting the cell housing of one cell withthe cell housing of an adjacent cell (e.g., cells that are connectedtogether in an approximately horizontal packing plane). In some cases,the cells are connected to each other by joining features that are partof and/or connected to the cell body (e.g., tabs protruding from themain portion of the cell body). A module can include a plurality ofcells in parallel. A module can comprise any number of cells, e.g., atleast about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20 or more cells. In some cases, a module comprises at least about4, 9, 12 or 16 cells. In some cases, a module is capable of storinggreater than or equal to about 700 Watt-hours of energy and/ordelivering at least about 175 Watts of power. In some cases, a module iscapable of storing at least about 1080 Watt-hours of energy and/ordelivering at least about 500 Watts of power. In some cases, a module iscapable of storing at least about 1080 Watt-hours of energy and/ordelivering at least about 200 Watts (e.g., greater than or equal toabout 500 Watts) of power. In some cases, a module can include a singlecell.

A pack can comprise modules that are attached through differentelectrical connections (e.g., vertically). A pack can comprise anynumber of modules, e.g., at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more modules. In some cases, apack comprises at least about 3 modules. In some cases, a pack iscapable of storing at least about 2 kilo-Watt-hours of energy and/ordelivering at least about 0.4 kilo-Watts (e.g., at least about 0.5kilo-Watts or 1.0 kilo-Watts) of power. In some cases, a pack is capableof storing at least about 3 kilo-Watt-hours of energy and/or deliveringat least about 0.75 kilo-Watts (e.g., at least about 1.5 kilo-Watts) ofpower. In some cases, a pack comprises at least about 6 modules. In somecases, a pack is capable of storing greater than or equal to about 6kilo-Watt-hours of energy and/or delivering at least about 1.5kilo-Watts (e.g., greater than or equal to about 3 kilo-Watts) of power.

A core can comprise a plurality of modules or packs that are attachedthrough different electrical connections (e.g., in series and/orparallel). A core can comprise any number of modules or packs, e.g., atleast about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,36, 37, 38, 39, 40, 45, 50 or more packs. In some cases, the core alsocomprises mechanical, electrical, and thermal systems that allow thecore to efficiently store and return electrical energy in a controlledmanner. In some cases, a core comprises at least about 12 packs. In somecases, a core is capable of storing at least about 25 kilo-Watt-hours ofenergy and/or delivering at least about 6.25 kilo-Watts of power. Insome cases, a core comprises at least about 36 packs. In some cases, acore is capable of storing at least about 200 kilo-Watt-hours of energyand/or delivering at least about 40, 50, 60, 70, 80, 90 or 100kilo-Watts or more of power.

A core enclosure (CE) can comprise a plurality of cores that areattached through different electrical connections (e.g., in seriesand/or parallel). A CE can comprise any number of cores, e.g., at leastabout 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,20 or more cores. In some cases, the CE contains cores that areconnected in parallel with appropriate by-pass electronic circuitry,thus enabling a core to be disconnected while continuing to allow theother cores to store and return energy. In some cases, a CE comprises atleast 4 cores. In some cases, a CE is capable of storing at least about100 kilo-Watt-hours of energy and/or delivering greater than or equal toabout 25 kilo-Watts of power. In some cases, a CE comprises 4 cores. Insome cases, a CE is capable of storing greater than or equal to about100 kilo-Watt-hours of energy and/or delivering greater than or equal toabout 25 kilo-Watts of power. In some cases, a CE is capable of storinggreater than or equal to about 400 kilo-Watt-hours of energy and/ordelivering at least about 80 kilo-Watts, e.g., greater than or equal toabout 80, 100, 120, 140, 160, 180, 200, 250 or 300 kilo-Watts or more ofpower.

A system can comprise a plurality of cores or CEs that are attachedthrough different electrical connections (e.g., in series and/orparallel). A system can comprise any number of cores or CEs, e.g., atleast about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,19, 20 or more cores. In some cases, a system comprises 20 CEs. In somecases, a system is capable of storing greater than or equal to about 2mega-Watt-hours of energy and/or delivering at least about 400kilo-Watts (e.g., about or at least about 500 kilo-Watts or 1000kilo-Watts) of power. In some cases, a system comprises 5 CEs. In somecases, a system is capable of storing greater than or equal to about 2mega-Watt-hours of energy and/or delivering at least about 400kilo-Watts, e.g., at least about 400, 500, 600, 700, 800, 900, 1,000,1,200, 1,500, 2,000, 2,500, 3,000 or 5,000 kilo-Watts or more of power.

A group of cells (e.g., a core, a CE, a system, etc.) with a givenenergy capacity and power capacity (e.g., a CE or a system capable ofstoring a given amount of energy) may be configured to deliver at leastabout 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95%, or about 100%of a given (e.g., rated) power level. For example, a 1000 kW system maybe capable of also operating at 500 kW, but a 500 kW system may not beable to operate at 1000 kW. In some cases, a system with a given energycapacity and power capacity (e.g., a CE or a system capable of storing agiven amount of energy) may be configured to deliver less than about100%, 110%, 125%, 150%, 175% or 200% of a given (e.g., rated) powerlevel, and the like. For example, the system may be configured toprovide more than its rated power capacity for a period of time that isless than the time it may take to consume its energy capacity at thepower level that is being provided (e.g., provide power that is greaterthan the rated power of the system for a period of time corresponding toless than about 1%, 10% or 50% of its rated energy capacity).

A battery can comprise one or more electrochemical cells connected inseries and/or parallel. A battery can comprise any number ofelectrochemical cells, modules, packs, cores, CEs or systems. A batterymay undergo at least one charge/discharge or discharge/charge cycle(“cycle”).

A battery can comprise one or more (e.g., a plurality of)electrochemical cells. The cell(s) can include housings. Individualcells can be electrically coupled to one another in series and/or inparallel. In series connectivity, the positive terminal of a first cellis connected to a negative terminal of a second cell. In parallelconnectivity, the positive terminal of a first cell can be connected toa positive terminal of a second, and/or additional, cell(s). Similarly,cell modules, packs, cores, CEs and systems can be connected in seriesand/or in parallel in the same manner as described for cells.

Reference will now be made to the figures, wherein like numerals referto like parts throughout. It will be appreciated that the figures andfeatures therein are not necessarily drawn to scale.

With reference to FIG. 1, an electrochemical cell (A) is a unitcomprising an anode and a cathode. The cell may comprise an electrolyteand be sealed in a housing as described herein. In some cases, theelectrochemical cells can be stacked (B) to form a battery (i.e., acompilation of one or more electrochemical cells). The cells can bearranged in parallel, in series, or both in parallel and in series (C).Further, as described in greater detail elsewhere herein, the cells canbe arranged in groups (e.g., modules, packs, cores, CEs, systems, or anyother group comprising one or more electrochemical cells). In somecases, such groups of electrochemical cells may allow a given number ofcells to be controlled or regulated together at the group level (e.g.,in concert with or instead of regulation/control of individual cells).

Electrochemical cells of the disclosure (e.g., Type 1 cell operated inType 2 mode, Type 1 cell operated in Type 1 mode, or Type 2 cell) may becapable of storing, receiving input of (“taking in”) and/or discharginga suitably large amount of energy (e.g., substantially large amounts ofenergy). In some instances, a cell is capable of storing, taking inand/or discharging greater than or equal to about 1 watt-hour (Wh), 5Wh, 25 Wh, 50 Wh, 100 Wh, 250 Wh, 500 Wh, 1 kilo-Watt-hour (kWh), 1.5kWh, 2 kWh, 3 kWh, 5 kWh, 10 kWh, 15 kWh, 20 kWh, 30 kWh, 40 kWh or 50kWh. It is recognized that the amount of energy stored in anelectrochemical cell and/or battery may be less than the amount ofenergy taken into the electrochemical cell and/or battery (e.g., due toinefficiencies and losses). A cell can have such energy storagecapacities upon operating at any of the current densities herein.

The cell can have a suitable energy storage capacity. In an example, acell comprises an anode and a cathode. The cell can be capable ofstoring at least about 10 Wh of energy. At least one of the anode andthe cathode can be a liquid metal. In another example, anelectrochemical cell comprises an electrically conductive housingcomprising a liquid metal (including liquid metal alloys) that is liquidat an operating temperature of, for example, at least about 200° C. Theelectrochemical cell may be capable of storing at least about 50 Wh or270 Wh of energy. The liquid metal can be configured (e.g., as part ofan electrochemical cell) to store/release charge during charge/dischargeof the electrochemical cell. The electrochemical cell can comprise aconductor in electrical contact with the liquid metal. The conductor canprotrude through the electrically conductive housing through an aperturein the electrically conductive housing. The electrochemical cell cancomprise a seal that seals the conductor to the electrically conductivehousing. In some cases, the seal electrically isolates the conductorfrom the electrically conductive housing.

A cell can be capable of providing a current at a current density of atleast about 10 milli-amperes per square centimeter (mA/cm²), 20 mA/cm²,30 mA/cm², 40 mA/cm², 50 mA/cm², 60 mA/cm², 70 mA/cm², 80 mA/cm², 90mA/cm²,100 mA/cm², 200 mA/cm², 300 mA/cm², 400 mA/cm², 500 mA/cm², 600mA/cm², 700 mA/cm², 800 mA/cm², 900 mA/cm², 1 A/cm², 2 A/cm², 3 A/cm², 4A/cm², 5 A/cm² or 10 A/cm², where the current density is determinedbased on the effective cross-sectional area of the electrolyte and wherethe cross-sectional area is the area that is orthogonal to the net flowdirection of ions through the electrolyte during charge or dischargingprocesses. In some instances, a cell can be capable of operating at adirect current (DC) efficiency of at least about 10%, 20%, 30%, 35%,40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 90%, 95%, and the like. Insome instances, a cell can be capable of operating at a chargeefficiency (e.g., Coulombic charge efficiency) of at least about 10%,20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, 95%, 98%, 99%, 99.5%,99.9%, 99.95%, 99.99%, and the like.

In a charged state, electrochemical cells of the disclosure (e.g., Type1 cell operated in Type 2 mode, Type 1 cell operated in Type 1 mode, orType 2 cell) can have (or can operate at) a voltage of at least about 0V, 0.1 V, 0.2 V, 0.3 V, 0.4 V, 0.5 V, 0.6 V, 0.7 V, 0.8 V, 0.9 V, 1.0 V,1.1 V, 1.2 V, 1.3 V, 1.4 V, 1.5 V, 1.6 V, 1.7 V, 1.8 V, 1.9 V, 2.0 V,2.1 V, 2.2 V, 2.3 V, 2.4 V, 2.5 V, 2.6 V, 2.7 V, 2.8 V, 2.9 V or 3.0 V.In some cases, a cell can have an open circuit voltage (OCV) of at leastabout 0.2 V, 0.3 V, 0.4 V, 0.5 V, 0.6 V, 0.7 V, 0.8 V, 0.9 V, 1.0 V, 1.1V, 1.2 V, 1.3 V, 1.4 V, 1.5 V, 1.6 V, 1.7 V, 1.8 V, 1.9 V, 2.0 V, 2.1 V,2.2 V, 2.3 V, 2.4 V, 2.5 V, 2.6 V, 2.7 V, 2.8 V, 2.9 V or 3.0 V. In anexample, a cell has an open circuit voltage greater than about 0.5 V, 1V, 2 V or 3 V. In some cases, a charge cutoff voltage (CCV) of a cell isfrom greater than or equal to about 0.5 V to 1.5 V, 1 V to 3 V, 1.5 V to2.5 V, 1.5 V to 3 V or 2 V to 3 V in a charged state. In some cases, acharge cutoff voltage (CCV) of a cell is at least about 0.5 V, 0.6 V,0.7 V, 0.8 V, 0.9 V, 1.0 V, 1.1 V, 1.2 V, 1.3 V, 1.4 V, 1.5 V, 1.6 V,1.7 V, 1.8 V, 1.9 V, 2.0 V, 2.1 V, 2.2 V, 2.3 V, 2.4 V, 2.5 V, 2.6 V,2.7 V, 2.8 V, 2.9 V or 3.0 V. In some cases, a voltage of a cell (e.g.,operating voltage) is between about 0.5 V and 1.5 V, 1 V and 2 V, 1 Vand 2.5 V, 1.5 V and 2.0 V, 1 V and 3 V, 1.5 V and 2.5 V, 1.5 V and 3 Vor 2 V and 3 V in a charged state. A cell can provide such voltage(s)(e.g., voltage, OCV and/or CCV) upon operating at up to and exceedingabout 10 cycles, 20 cycles, 30 cycles, 40 cycles, 50 cycles, 100 cycles,200 cycles, 300 cycles, 400 cycles, 500 cycles, 600 cycles, 700 cycles,800 cycles, 900 cycles, 1,000 cycles, 2,000 cycles, 3,000 cycles, 4,000cycles, 5,000 cycles, 10,000 cycles, 20,000 cycles, 50,000 cycles,100,000 cycles or 1,000,000 or more cycles (also “charge/dischargecycles” herein).

In some cases, the limiting factor on the number of cycles may bedependent on, for example, the housing and/or the seal as opposed to thechemistry of the negative electrode, electrolyte and/or the positiveelectrode. The limit in cycles may be dictated not by theelectrochemistry, but by the degradation of non-active components of thecell, such as the container or seal. A cell can be operated without asubstantial decrease in capacity. The operating lifetime of a cell canbe limited, in some cases, by the life of the container, seal and/or capof the cell. During operation at an operating temperature of the cell,the cell can have a negative electrode, electrolyte and positiveelectrode in a liquid (or molten) state.

An electrochemical cell of the present disclosure can have a responsetime of any suitable value (e.g., suitable for responding todisturbances in the power grid). In some instances, the response time isless than or equal to about 100 milliseconds (ms), 50 ms, 10 ms, 1 ms,and the like. In some cases, the response time is at most about 100 ms,50 ms, 10 ms, 1 ms, and the like.

A compilation or array of cells (e.g., battery) can include any suitablenumber of cells, such as at least about 2, 5, 10, 50, 100, 500, 1000,5000, 10000, and the like. In some examples, a battery includes at leastabout 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90,100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 5000, 10,000,20,000, 50,000, 100,000, 500,000 or 1,000,000 cells.

In some implementations, one or more types of cells can be included inenergy storage systems of the present disclosure. For example, an energystorage device can comprise Type 2 cells or a combination of Type 1cells and Type 2 cells (e.g., 50% Type 1 cells and 50% Type 2 cells).Such cells can be operated under Type 2 mode. In some cases, a firstportion of the cells may be operated in Type 1 mode, and a secondportion of the cells may be operated in Type 2 mode.

Batteries of the disclosure may be capable of storing and/or taking in asuitably large amount of energy (e.g., a substantially large amount ofenergy) for use with a power grid (i.e., a grid-scale battery) or otherloads or uses. In some instances, a battery is capable of storing,taking in and/or discharging greater than or equal to about 1 watt-hour(Wh), 5 Wh, 25 Wh, 50 Wh, 100 Wh, 250 Wh, 500 Wh, 1 kilo-Watt-hour(kWh), 1.5 kWh, 2 kWh, 3 kWh, 5 kWh, 10 kWh, 15 kWh, 20 kWh, 25 kWh, 30kWh, 40 kWh, 50 kWh, 100 kWh, 500 kWh, 1 mega-Watt-hour (MWh), 1.5 MWh,2 MWh, 3 MWh, 4 MWh, 5 MWh, 10 MWh, 25 MWh, 50 MWh or 100 MWh.

The battery can be any suitable size (e.g., have a suitable energystorage capacity). In an example, a battery comprises a plurality ofelectrochemical cells connected in series. The battery can be capable ofstoring at least about 10 kWh of energy and can have an operatingtemperature of, for example, at least about 250° C. Each of theelectrochemical cells can have at least one liquid metal electrode. Insome cases, the battery is capable of storing at least about 30 kWh or100 kWh of energy. In another example, a group of cells is capable ofstoring at least about 10 kWh of energy.

In some instances, the cells and cell housings are stackable. Anysuitable number of cells can be stacked. Cells can be stackedside-by-side, on top of each other, or both. In some instances, at leastabout 3, 6, 10, 50, 100 or 500 cells are stacked. In some cases, a stackof 100 cells is capable of storing and/or taking in at least 50 kWh ofenergy. A first stack of cells (e.g., 10 cells) can be electricallyconnected to a second stack of cells (e.g., another 10 cells) toincrease the number of cells in electrical communication (e.g., 20 inthis instance). In some instances, the energy storage device comprises astack of 1 to 10, 11 to 50, 51 to 100 or more electrochemical cells.

An electrochemical energy storage device can include one or moreindividual electrochemical cells. An electrochemical cell can be housedin a container, which can include a container lid (e.g., cell cap) andseal component. The device can include at least 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 20, 30, 40, 50, 100, 200, 300, 400, 500, 1000, 10,000, 100,000 or1,000,000 cells. The container lid may utilize, for example, a seal(e.g., annular dielectric gasket) to electrically isolate the containerfrom the container lid. Such a component may be constructed from anelectrically insulating material, such as, for example, glass, oxideceramics, nitride ceramics, chalcogenides, or a combination thereof(e.g., ceramic, silicon oxide, aluminum oxide, nitrides comprising boronnitride, aluminum nitride, zirconium nitride, titanium nitride, carbidescomprising silicon carbide, titanium carbide, or other oxides comprisingof lithium oxide, calcium oxide, barium oxide, yttrium oxide, siliconoxide, aluminum oxide, or lithium nitride, lanthanum oxide, or anycombinations thereof).

A cell can be hermetically or non-hermetically sealed. Further, in agroup of cells (e.g., a battery), each of the cells can be hermeticallyor non-hermetically sealed. If the cells are not hermetically sealed,the group of cells or battery (e.g., several cells in series orparallel) can be hermetically sealed.

The seal may be made hermetic by one or more methods. For example, theseal may be subject to relatively high compressive forces (e.g., greaterthan about 1,000 psi or 10,000 psi) between the container lid and thecontainer in order to provide a seal in addition to electricalisolation. Alternatively, the seal may be bonded through a weld, abraze, or other chemically adhesive material that joins relevant cellcomponents to the insulating sealant material.

In an example, a cell housing comprises an electrically conductivecontainer, a container aperture and a conductor in electricalcommunication with a current collector. The conductor may pass throughthe container aperture and can be electrically isolated from theelectrically conductive container. The housing may be capable ofhermetically sealing a cell which is capable of storing at least about10 Wh of energy.

FIG. 2 schematically illustrates a battery that comprises anelectrically conductive housing 201 and a conductor 202 in electricalcommunication with a current collector 203. The battery of FIG. 2 can bea cell of an energy storage device. The conductor can be electricallyisolated from the housing and can protrude through the housing throughan aperture in the housing such that the conductor of a first cell is inelectrical communication with the housing of a second cell when thefirst and second cells are stacked.

In some cases, a cell comprises a negative current collector, a negativeelectrode, an electrolyte, a positive electrode and a positive currentcollector. The negative electrode can be part of the negative currentcollector. As an alternative, the negative electrode is separate from,but otherwise kept in electrical communication with, the negativecurrent collector. The positive electrode can be part of the positivecurrent collector. As an alternative, the positive electrode can beseparate from, but otherwise kept in electrical communication with, thepositive current collector.

A cell can comprise an electrically conductive housing and a conductorin electrical communication with a current collector. The conductorprotrudes through the housing through an aperture in the housing and maybe electrically isolated from the housing.

A cell housing may comprise an electrically conductive container and aconductor in electrical communication with a current collector. Theconductor may protrude through the housing and/or container through anaperture in the container and may be electrically isolated from thecontainer. The conductor of a first housing may contact the container ofa second housing when the first and second housings are stacked.

In some instances, the area of the aperture through which the conductorprotrudes from the housing and/or container is small relative to thearea of the housing and/or container. The ratio of the area of theaperture to the area of the container and/or housing may be less than orequal to about 0.5, 0.4, 0.3, 0.2, 0.15, 0.1, 0.05, 0.01, 0.005 or 0.001(e.g., less than about 0.1).

The housing can be capable of enclosing a cell that is capable ofstoring, taking in and/or discharging any suitable amount of energy, asdescribed in greater detail elsewhere herein. For example, the housingcan be capable of enclosing a cell that is capable of storing, taking inand/or discharging less than about 100 Wh, equal to about 100 Wh, morethan about 100 Wh or at least about 10 Wh or 25 Wh of energy.

FIG. 3 is a cross-sectional side view of an electrochemical cell orbattery 300 comprising a housing 301, an electrically conductivefeed-through (i.e., conductor, such as a conductor rod) 302 that passesthrough an aperture in the housing and is in electrical communicationwith a liquid metal negative electrode 303, a liquid metal positiveelectrode 305, and a liquid salt electrolyte 304 between the liquidmetal electrodes 303, 305. The cell or battery 300 can be configured foruse with cell chemistries operated under a low voltage mode (“Type 1mode”) or high voltage mode (“Type 2 mode”), as disclosed elsewhereherein. The conductor 302 may be electrically isolated from the housing301 (e.g., using electrically insulating seals). The negative currentcollector 307 may comprise foam material 303 that behaves like a sponge,and the negative electrode liquid metal soaks into the foam. The liquidmetal negative electrode 303 is in contact with the liquid saltelectrolyte 304. The liquid salt electrolyte is also in contact with thepositive liquid metal electrode 305. The positive liquid metal electrode305 can be in electrical communication with the housing 301 along theside walls and/or along the bottom end wall of the housing. In someexamples, the electrochemical cell or battery 300 may comprise two ormore conductors passing through one or more apertures and in electricalcommunication with the liquid metal negative electrode 303. In someinstances, a separator structure (not shown) may be arranged within theelectrolyte 304 between the liquid negative electrode 303 and the(liquid) positive electrode 305.

The housing may include a container and a container lid (e.g., cellcap). The container and container lid may be connected mechanically(e.g., welded). In some cases, the mechanical connection may comprise achemical connection. In some instances, the container lid iselectrically isolated from the container. The cell lid may or may not beelectrically isolated from the negative current lead in such instances.In some instances, the container lid is electrically connected to thecontainer (e.g., cell body). The cell lid may then be electricallyisolated from the negative current lead. During operation (e.g., when ina molten state), the container lid and the container can be connectedelectronically (e.g., through a direct electrical connection, such as,for example, via a welded lid-to-cell body joint, or ionically throughthe electrolyte and the electrodes). The negative current lead may beelectrically isolated from the container and/or container lid (e.g.,cell cap), via, for example, the use of an electrically insulatinghermetic seal. In some examples, an electrically insulating barrier(e.g., seal) may be provided between the negative current lead and thecontainer lid. The seal can be in the form of a gasket, for example, andplaced between the container lid, and the container. The housing 301 canbe constructed from an electrically conductive material such as, forexample, steel, iron, stainless steel, low carbon steel, graphite,nickel, nickel based alloys, titanium, aluminum, molybdenum, tungsten,or conductive compounds such as nitrides (e.g., silicon carbide ortitanium carbide), or a combination thereof (e.g., alloy).

The housing 301 can comprise a housing (or container) interior 306. Thehousing interior 306 may include, but is not limited to, a sheath (e.g.,a graphite sheath), a coating, a crucible (e.g., a graphite crucible), asurface treatment, a lining, or any combination thereof. In one example,the housing interior 306 is a sheath. In another example, the housinginterior 306 is a crucible. In yet another example, the housing interior306 is a coating or surface treatment. The housing interior 306 may bethermally conductive, thermally insulating, electrically conductive,electrically insulating, or any combination thereof. For example, thehousing interior (e.g., sheath, crucible and/or coating) 306 can beconstructed from a material such as, for example, graphite, carbide(e.g., SiC, TiC, etc.), nitride (e.g., BN, TiN, etc.), alumina, titania(TiO₂), silica (SiO₂), magnesia, boron nitride, rare-earth oxides (e.g.,a lanthanide oxide or a mixture of lanthanide oxides, such as, forexample, neodymium oxide (Nd₂O₃), cerium oxide (CeO₂), lanthanum oxide(La₂O₃), samarium oxide (Sm₂O₃), or any combination thereof), a mixedoxide (e.g., any combination of calcium oxide, aluminum oxide, siliconoxide, lithium oxide, magnesium oxide, lanthanide oxide, neodymiumoxide, etc.), or any combination thereof. In some cases, the housinginterior 306 may be provided for protection of the housing (e.g., forprotecting the stainless steel material of the housing from corrosion).In some cases, the housing interior can be anti-wetting to the liquidmetal positive electrode. In some cases, the housing interior can beanti-wetting to the liquid electrolyte. For example, the housinginterior 306 can be used to limit or prevent corrosion of the containerand/or to limit or prevent wetting of the cathode material up the sidewall, and may be constructed from an electrically conductive material,such as steel, stainless steel, tungsten, molybdenum, nickel,nickel-based alloys, graphite, titanium, or titanium nitride.

The housing may comprise a lining component or lining (e.g., anelectrically insulating or electrically conductive lining component thatis thinner than the cell body) of a separate metal or compound, or acoating (e.g., an electrically insulating or electrically conductivecoating), such as, for example, a steel housing with a graphite liningor with a nitride coating or lining (e.g., boron nitride, aluminumnitride, titanium nitride), a carbide coating or lining (e.g., siliconcarbide, titanium carbide), a rare-earth oxide coating or lining (e.g.,Nd₂O₃, CeO₂, La₂O₃), or a coating or lining of titanium or other stable(e.g., chemically stable) metal (e.g., Ni, B). The lining and/or coatingcan exhibit favorable properties and functions, including surfaces thatare anti-wetting to the positive electrode liquid metal. For example,the housing interior may be anti-wetting (e.g., substantiallynon-wetting) to the liquid cathode metal, thereby limiting or preventingit from wetting up the side-wall of the container. In some cases, thelining and/or coating may include an oxide material (e.g., yttriumoxide, zirconium oxide, samarium oxide, neodymium oxide, cerium oxide,calcium oxide or magnesium oxide) that is stable (e.g., chemicallystable) with one or more portions of the cell (e.g., molten salt,reactive metal such as lithium, etc.) that are in liquid or solidcontact with the oxide material. In some cases, the lining and/orcoating (e.g., lining and/or coating comprising magnesium oxide, yttriumoxide, neodymium oxide, lanthanum oxide or cerium oxide) may have acoefficient of thermal expansion (CTE) that is similar or about equal tothe CTE of the housing material (e.g., stainless steel). For example,some rare-earth oxides (e.g., Nd₂O₃) have a CTE that closely matches theCTE of stainless steel while also being stable (e.g., thermodynamicallystable) with reactive materials (e.g., lithium) and/or the molten saltsherein. The lining and/or coating may be a separate cell component thatis physically placed within the housing, or the lining may be directlyformed onto the housing surface to form a coating (e.g., via plasmaspray coating, sputtering, precipitation-based coating process,thermally grown oxidation layer, or any other coating processes). TheCTE of the lining and/or coating may differ from the CTE of the housingby less than about 1%, 5%, 10%, 20% or 50%. The lining and/or coatingmay comprise a mixture of different materials that has a CTE that moreclosely matches that of the housing compared to the CTE of one or more(e.g., any) individual constituent materials (e.g., positive electrodematerial, negative electrode material, electrolyte material). Forexample, the lining and/or coating may comprise a mixture that has a CTEthat matches the CTE of the housing at least about 5%, 10%, 15%, 25%,50% or 75% closer than the CTE of one or more (e.g., any) individualconstituent materials. The lining and/or coating may protect thecontainer from higher voltages (e.g., voltages greater than about 1 V,1.5 V, 2 V or 2.5 V). The lining and/or coating may be used instead of acrucible (e.g., a graphite crucible), which may, for example, reducecell cost and increase cell capacity. In some cases, additives to thelining and/or coating (e.g., Ni or other ductile metals) may beincluded. The additives may provide increased ductility and/or lowerelastic modulus of the housing interior material. In some cases, thelining (e.g., graphite lining) and/or coating can be dried by heatingabove room temperature in air or dried in a vacuum oven before or afterbeing placed inside the cell housing. Drying or heating the liningand/or coating can remove moisture from the lining and/or coating priorto adding the electrolyte, positive electrode, or negative electrode tothe cell housing. Any aspects of the disclosure described in relation toa coating may equally apply to a lining or a surface treatment at leastin some configurations, and vice versa.

The housing 301 may include a thermally and/or electrically insulatingsheath or crucible 306. In this configuration, the negative electrode303 may extend laterally between the side walls of the housing 301defined by the sheath or crucible without being electrically connected(i.e., shorted) to the positive electrode 305. Alternatively, thenegative electrode 303 may extend laterally between a first negativeelectrode end 303 a and a second negative electrode end 303 b. In thisconfiguration, the sheath or crucible may or may not be thermally and/orelectrically insulating. For example, the sheath or crucible may beelectrically conductive. When an electrically insulating sheath orcrucible 306 is not provided, the negative electrode 303 may have adiameter (or other characteristic dimension, illustrated in FIG. 3 asthe distance from 303 a to 303 b) that is less than the diameter (orother characteristic dimension such as width for a cuboid container,illustrated in FIG. 3 as the distance D) of the cavity defined by thehousing 301.

As shown in the example in FIG. 3, the sheath or other housing interior(e.g., crucible, coating) 306 can have an annular cross-sectionalgeometry that can extend laterally between a first sheath end 306 a anda second sheath end 306 b. The sheath may be dimensioned (illustrated inFIG. 3 as the distance from 306 a to 306 b) such that the sheath is incontact and pressed up against the side walls of the cavity defined bythe housing cavity 301. In some cases, the sheath (e.g., graphitesheath) can be dried by heating above room temperature in air or driedin a vacuum oven before or after being placed inside the cell housing.Drying or heating the sheath may remove moisture from the sheath priorto adding the electrolyte, positive electrode, or negative electrode tothe cell housing.

The cell may comprise an electrically conductive crucible or coatingthat lines the side walls and bottom inner surface of the cell housing,referred to as a cell housing liner, preventing direct contact of thepositive electrode with the cell housing. In an example, the cell cancomprise a cell housing liner instead of a sheath. In another example,the sheath may be very thin and can be a coating. The cell housing linermay limit or prevent wetting of the positive electrode between the cellhousing and the cell housing liner or sheath and may prevent directcontact of the positive electrode on the bottom surface of the cellhousing. The cell housing liner or sheath (e.g., coating) can cover justthe inside of the walls, and/or, can also cover the bottom of the insideof the container. The cell housing liner or sheath may not fit perfectlywith the housing 301 which may hinder the flow of current between thecell housing liner or sheath and the cell housing. To ensure adequateelectronic conduction between the cell housing liner or sheath and thecell housing, a liquid of metal that has a low melting point (e.g., Pb,Sn, Bi), can be used to provide a strong electrical connection betweenthe cell housing liner or sheath (e.g., sheath/coating) and the cellhousing. This layer can allow for easier fabrication and assembly of thecell. For example, the crucible can be made to be in electronic contactwith the cell housing using a thin layer of a conductive liquid metal orsemi-solid metal alloy located between the crucible and the cellhousing, such as the elements Pb, Sn, Sb, Bi, Ga, In, Te, or acombination thereof.

The housing 301 can also include a first (e.g., negative) currentcollector or lead 307 and a second (e.g., positive) current collector308. The negative current collector 307 may be constructed from anelectrically conductive material such as, for example, nickel-iron(Ni—Fe) foam, stainless steel foam, Ni-plated iron foam, foam of anothermetal alloy, perforated steel disk, sheets of corrugated steel, sheetsof expanded metal mesh, etc. The negative current collector 307 may beconfigured as a plate or foam that can extend laterally between a firstcollector end 307 a and a second collector end 307 b. The negativecurrent collector 307 may have a collector diameter that is less than orsimilar to the diameter of the cavity defined by the housing 301. Insome cases, the negative current collector 307 may have a collectordiameter (or other characteristic dimension, illustrated in FIG. 3 asthe distance from 307 a to 307 b) that is less than or similar to thediameter (or other characteristic dimension, illustrated in FIG. 3 asthe distance from 303 a to 303 b) of the negative electrode 303. Thepositive current collector 308 may be configured as part of the housing301; for example, the bottom end wall of the housing may be configuredas the positive current collector 308, as illustrated in FIG. 3.Alternatively, the current collector may be discrete from the housingand may be electrically connected to the housing. In some cases, thepositive current collector may not be electrically connected to thehousing. The present disclosure is not limited to any particularconfigurations of the negative and/or positive current collectorconfigurations.

The negative electrode 303 can be contained within the negative currentcollector (e.g., foam) 307. In this configuration, the electrolyte layercomes up in contact with the bottom, sides, and/or the top of the foam307. The metal contained in the foam (i.e., the negative electrodematerial) can be held away from the sidewalls of the housing 301, suchas, for example, by the absorption and retention of the liquid metalnegative electrode into the foam, thus allowing the cell to run withoutthe insulating sheath 306. In some cases, a graphite sheath or graphitecell housing liner (e.g., graphite crucible) may be used to prevent thepositive electrode from wetting up along the side walls, which canprevent shorting of the cell.

Current may be distributed substantially evenly across a positive and/ornegative liquid metal electrode in contact with an electrolyte along asurface (i.e., the current flowing across the surface may be uniformsuch that the current flowing through any portion of the surface doesnot substantially deviate from an average current density). In someexamples, the maximum density of current flowing across an area of thesurface is less than or equal to about 105%, 115%, 125%, 150%, 175%,200%, 250% or 300% of the average density of current flowing across thesurface. In some examples, the minimum density of current flowing acrossan area of the surface is greater than or equal to about 50%, 60%, 70%,80%, 90% or 95% of the average density of current flowing across thesurface.

Viewed from a top or bottom direction, as indicated respectively by “TOPVIEW” and “BOTTOM VIEW” in FIG. 3, the cross-sectional geometry of thecell or battery 300 can be circular, elliptical, square, rectangular,polygonal, curved, symmetric, asymmetric or any other compound shapebased on design requirements for the battery. In an example, the cell orbattery 300 is axially symmetric with a circular or squarecross-section. Components of cell or battery 300 (e.g., component inFIG. 3) may be arranged within the cell or battery in an axiallysymmetric fashion. In some cases, one or more components may be arrangedasymmetrically, such as, for example, off the center of the axis 309.

The combined volume of positive and negative electrode material (thecombined volume of anode and cathode material) may be greater than orequal to about 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 95% ofthe volume of the battery (e.g., as defined by the outer-most housing ofthe battery, such as a shipping container). The combined volume of anodeand cathode material may be at least about 5%, 10%, 20%, 30%, 40%, 60%or 75% of the volume of the cell. The combined volume of the positiveand negative electrodes material may increase or decrease (e.g., inheight) during operation due to growth or expansion, or shrinkage orcontraction, respectively, of the positive or negative electrode. In anexample, during discharge, the volume of the negative electrode (anodeduring discharge) may be reduced due to transfer of the negativeelectrode material to the positive electrode (cathode during discharge),wherein the volume of the positive electrode is increased (e.g., as aresult of an alloying reaction). The volume reduction of the negativeelectrode may or may not equal the volume increase of the positiveelectrode. The positive and negative electrode materials may react witheach other to form a solid or semi-solid mutual reaction compound (also“mutual reaction product” herein), which may have a density that is thesame, lower, or higher than the densities of the positive and/ornegative electrode materials. Although the mass of material in theelectrochemical cell or battery 300 may be constant, one, two or morephases (e.g., liquid or solid) may be present, and each such phase maycomprise a certain material composition (e.g., an alkali metal may bepresent in the materials and phases of the cell at varyingconcentrations: a liquid metal negative electrode may contain a highconcentration of an alkali metal, a liquid metal positive electrode maycontain an alloy of the alkali metal and the concentration of the alkalimetal may vary during operation, and a mutual reaction product of thepositive and negative liquid metal electrodes may contain the alkalimetal at a fixed or variable stoichiometry). The phases and/or materialsmay have different densities. As material is transferred between thephases and/or materials of the electrodes, a change in combinedelectrode volume may result.

In some cases, a cell can include one or more alloyed products that areliquid, semi-liquid (or semi-solid), or solid. The alloyed products canbe immiscible (or, in some cases, soluble) with the negative electrode,positive electrode and/or electrolyte. The alloyed products can formfrom electrochemical processes during charging or discharging of a cell.

An alloyed product can include an element constituent of a negativeelectrode, positive electrode and/or electrolyte. An alloyed product canhave a different density than the negative electrode, positive electrodeor electrolyte, or a density that is similar or substantially the same.The location of the alloyed product can be a function of the density ofthe alloyed product compared to the densities of the negative electrode,electrolyte and positive electrode. The alloyed product can be situatedin the negative electrode, positive electrode or electrolyte, or at alocation (e.g., interface) between the negative electrode and theelectrolyte or between the positive electrode and the electrolyte, orany combination thereof. In an example, an alloyed product is anintermetallic between the positive electrode and the electrolyte (see,for example, FIG. 4). In some cases, some electrolyte can seep inbetween the intermetallic and the positive electrode. In other examples,the alloyed product can be at other locations within the cell and beformed of a material of different stoichiometries/compositions,depending on the chemistry, temperature, and/or charge state of thecell.

FIG. 4 is a cross-sectional side view of an electrochemical cell orbattery 400 with an intermetallic layer 410. The intermetallic layer 410can include a mutual reaction compound of a material originating fromthe negative electrode 403 and positive electrode material 405. Forexample, a negative liquid metal electrode 403 can comprise an alkali oralkaline earth metal (e.g., Na, Li, K, Mg, or Ca), the positive liquidmetal electrode 405 can comprise one or more of transition metal,d-block (e.g., Group 12), Group IIIA, IVA, VA or VIA elements (e.g.,lead and/or antimony and/or bismuth), and the intermetallic layer 410can comprise a mutual reaction compound or product thereof (e.g., alkaliplumbide, antimonide or bismuthide, e.g., Na₃Pb, Li₃Sb, K₃Sb, Mg₃Sb₂,Ca₃Sb₂, or Ca₃Bi₂). An upper interface 410 a of the intermetallic layer410 is in contact with the electrolyte 404, and a lower interface 410 bof the intermetallic layer 410 is in contact with the positive electrode405. The mutual reaction compound may be formed during discharging at aninterface between a positive liquid metal electrode (liquid metalcathode in this configuration) 405 and a liquid salt electrolyte 404.The mutual reaction compound (or product) can be solid or semi-solid. Inan example, the intermetallic layer 410 can form at the interfacebetween the liquid metal cathode 405 and the liquid salt electrolyte404. In some cases, the intermetallic layer 410 may exhibit liquidproperties (e.g., the intermetallic may be semi-solid, or it may be of ahigher viscosity or density than one or more adjacent phases/materials).

The cell 400 comprises a first current collector 407 and a secondcurrent collector 408. The first current collector 407 is in contactwith the negative electrode 403, and the second current collector 408 isin contact with the positive electrode 405. The first current collector407 is in contact with an electrically conductive feed-through 402. Ahousing 401 of the cell 400 can include a thermally and/or electricallyinsulating sheath 406. In an example, the negative liquid metalelectrode 403 includes magnesium (Mg), the positive liquid metalelectrode 405 includes antimony (Sb), and the intermetallic layer 410includes Mg and Sb (Mg_(x)Sb, where ‘x’ is a number greater than zero),such as, for example, magnesium antimonide (Mg₃Sb₂). Cells with a Mg∥Sbchemistry may contain magnesium ions within the electrolyte as well asother salts (e.g., MgCl₂, NaCl, KCl, or a combination thereof). In somecases, in a discharged state, the cell is deficient in Mg in thenegative electrode and the positive electrode comprises and alloy ofMg—Sb. In such cases, during charging, Mg is supplied from the positiveelectrode, passes through the electrolyte as a positive ion, anddeposits onto the negative current collector as Mg. In some examples,the cell has an operating temperature of at least about 300° C., 350°C., 400° C., 450° C., 475° C., 500° C., 550° C., 600° C., 650° C., 700°C. or 750° C., and in some cases between about 650° C. and 750° C. In acharged state, all or substantially all the components of the cell canbe in a liquid state. Alternative chemistries exist, including Ca-Mg∥Bicomprising a calcium halide constituent in the electrolyte (e.g., CaF₂,KF, LiF, CaCl₂, KCl, LiCl, CaBr₂, KBr, LiBr, or combinations thereof)and operating, for example, above about 500° C., Ca-Mg∥Sb-Pb comprisinga calcium halide constituent in the electrolyte (e.g., CaF₂, KF, LiF,CaCl₂, KCl, LiCl, CaBr₂, KBr, LiBr, or combinations thereof) andoperating, for example, above about 500° C., Li∥Pb-Sb cells comprising alithium-ion containing halide electrolyte (e.g., LiF, LiCl, LiBr, orcombinations thereof) and operating, for example, between about 350° C.and about 550° C., and Na∥Pb cells comprising a sodium halide as part ofthe electrolyte (e.g., NaCl, NaBr, NaI, NaF, LiCl, LiF, LiBr, LiI, KCl,KBr, KF, KI, CaCl₂, CaF₂, CaBr₂, CaI₂, or combinations thereof) andoperating, for example, above about 300° C. In some cases, the productof the discharge reaction may be an intermetallic compound (e.g., Mg₃Sb₂for the Mg∥Sb cell chemistry, Li₃Sb for the Li∥Pb-Sb chemistry, Ca₃Bi₂for the Ca-Mg∥Bi chemistry, or Ca₃Sb₂ for the Ca-Mg∥Pb-Sb chemistry),where the intermetallic layer may develop as a distinct solid phase by,for example, growing and expanding horizontally along a direction xand/or growing or expanding vertically along a direction y at theinterface between the positive electrode and the electrolyte. The growthmay be axially symmetrical or asymmetrical with respect to an axis ofsymmetry 409 located at the center of the cell or battery 400. In somecases, the intermetallic layer is observed under Type 1 mode ofoperation but not Type 2 mode of operation. For example, theintermetallic layer (e.g., the intermetallic layer in FIG. 4) may notform during operation of a Type 2 cell.

A person of skill in the art will recognize that the battery housingcomponents may be constructed from materials other than the examplesprovided above. One or more of the electrically conductive batteryhousing components, for example, may be constructed from metals otherthan steel and/or from one or more electrically conductive composites.In another example, one or more of the electrically insulatingcomponents may be constructed from dielectrics other than theaforementioned glass, mica and vermiculite. The present inventiontherefore is not limited to any particular battery housing materials.

Cell Lid Assemblies and Adhesive Seals

Cell lid assemblies can use adhesive seals to achieve a gas tight andelectrically insulating seal. As seen in FIG. 5, a conductivefeed-through 501 can be electrically isolated from the housing and thehousing can be sealed by an adhesive sealing material 502 disposedbetween the feed-through and the housing. The adhesive sealing materialcan include any sealant material capable of adhering to the componentsof the cell lid assembly that are to be sealed.

In some cases, for cells that are sealed with adhesive dielectric seals,a pressure of less than 1 psi may be sufficient to maintain a gas tightseal. In some cases, at least a portion of the pressure can be suppliedby the weight of one or more electrochemical cells stacked upon eachother in a battery. The adhesive seal material can comprise a glass sealor a brazed ceramic, such as, for example, alumina with Cu—Ag brazealloy, or other ceramic-braze combination.

In a stacked battery configuration, it may be desirable to reduce headspace (e.g., inside a cell chamber or cavity) so that relatively more ofthe volume of the cell can comprise anode and cathode material (e.g.,such that the cell can have a higher energy storage capacity per unitvolume). In some instances, the height of the head space (e.g., asmeasured from the top of the feed-through to the top surface of theanode) is a small fraction of the height of the battery (e.g., asmeasured from the top of the feed-through to the bottom surface of thehousing). In some examples, the head space is at most or equal to about5%, 10%, 15%, 20% or 25% of the height of the battery.

In some examples, the electrolyte can have a thickness (measured as thedistance between negative electrode/electrolyte and positiveelectrode/electrolyte interfaces) of at least about 0.01 cm, 0.05 cm,0.1 cm, 0.5 cm, 0.8 cm, 1.0 cm, 1.3 cm, 1.5 cm, 2 cm, 3 cm, 4 cm, 5 cm,6 cm, 7 cm, 8 cm, 9 cm or 10 cm for a cell having a thickness of atleast about 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cmor more. In some examples, a cell has a thickness of at most about 3 cmor 4 cm, and an electrolyte with a thickness of at most about 1 cm or 2cm.

In some situations, the use of a few or only a single conductivefeed-through can result in uneven current distribution in an electrode(e.g., in the negative electrode). A plurality of conductivefeed-throughs (also “conductors” herein) can more evenly distribute thecurrent in the electrode. In some implementations, an electrochemicalenergy storage device comprises a housing, a liquid metal electrode, acurrent collector in contact with the liquid metal electrode, and aplurality of conductors that are in electrical communication with thecurrent collector and protrude through the housing through apertures inthe housing. In some examples, current is distributed substantiallyevenly across the liquid metal electrode.

In some examples, the liquid metal electrode is in contact with anelectrolyte along a surface (and/or interface) and the current flowingacross the surface (and/or interface) is uniform. The current flowingthrough any portion of the surface (and/or interface) may not deviatesubstantially from the average current through the surface. In someexamples, the maximum density of current flowing across an area of thesurface (and/or interface) is less than about 105%, 115%, 125%, 150%,175%, 200%, 250% or 300% of the average density of current flowingacross the surface (and/or interface). In some examples, the minimumdensity of current flowing across an area of the surface (and/orinterface) is greater than about 50%, 60%, 70%, 80%, 90% or 95% of theaverage density of current flowing across the surface (and/orinterface).

FIG. 6 shows examples of cells with multiple conductive feed-throughs.In these configurations, current collectors can be combined into ashared lid assembly for each cell. Such cell lid assemblies may be usedwith cells of any size. The electrochemical storage device and/orhousings can comprise any number of conductive feed-throughs (e.g., 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 ormore). In some cases, the conductive feed-throughs are separate (A). Insome cases, the conductive feed-throughs share a common upper portion(B).

Features and Properties of Seals

The seal can be an important part of a high temperature systemcontaining reactive metals (e.g., a liquid metal battery). Providedherein is a method for choosing materials suitable for forming a sealand methods for designing a suitable seal for a system containingreactive liquid metals or liquid metal vapors and/or reactive moltensalt(s) or reactive molten salt vapors such as, for example, a liquidmetal battery (e.g., based on the selection of these materials, andconsiderations of thermal, mechanical and electrical properties). Theseal can also be used as part of an electrically isolated feed-throughconnected to a vessel comprising reactive liquid metals or reactivemetal vapors for applications other than energy storage, such as fusionreactors comprising molten or high pressure Li vapor, or otherapplications that involve liquid sodium, potassium, and/or lithium. Theuse of stable ceramic and electronically conductive materials can alsobe appropriate for applications with reactive gases such as those usedin semiconductor material processing or device fabrication.

The seal can be electrically insulating and gas-tight (e.g., hermetic).The seals can be made of materials that are not attacked by the liquidand vapor phases of system/vessel components (e.g., cell components),such as, for example, molten sodium (Na), molten potassium (K), moltenmagnesium (Mg), molten calcium (Ca), molten lithium (Li), Na vapor, Kvapor, Mg vapor, Ca vapor, Li vapor, or any combination thereof. Themethod identifies a seal comprising an aluminum nitride (AlN) or siliconnitride (Si₃N₄) ceramic and an active alloy braze (e.g., Ti, Fe, Ni, B,Si or Zr alloy-based) as being thermodynamically stable with mostreactive metal vapors, thus allowing for the design of a seal that isnot appreciably attacked by metal or metal vapors.

In some implementations, the seal can physically separate the negativecurrent lead (e.g., a metal rod that extends into the cell cavity) fromthe positively charged cell body (e.g., the cell can (also “container”herein) and lid). The seal can act as an electrical insulator betweenthese cell components, and hermetically isolate the active cellcomponents (e.g., the liquid metal electrodes, the liquid electrolyte,and vapors of these liquids). In some cases, the seal prevents externalelements from entering the cell (e.g., moisture, oxygen, nitrogen, andother contaminants that may negatively affect the performance of thecell). Some examples of general seal specifications are listed inTABLE 1. Such specifications (e.g., properties and/or metrics) caninclude, but are not limited to, hermeticity, electrical insulation,durability, Coulombic efficiency (e.g., charge efficiency or round-tripefficiency), DC-DC efficiency, discharge time, and capacity fade rate.

TABLE 1 EXAMPLES OF GENERAL SEAL SPECIFICATIONS Specification Examplevalue The seal can have these properties under operating conditions:Hermetic <1 × 10−8 atm cc/s He total leak rate Electricallyinsulating >1 kOhm impedance across seal Durable maintain integrityfor >20 years Battery metrics: Coulombic efficiency >98% (@ ~200 mA/cm²)DC-DC efficiency >70% (@ ~200 mA/cm²) Discharge time 4-6 hours (@ ~200mA/cm²) Capacity fade rate <0.02%/cycle

The seal can be hermetic, for example, to a degree quantified by a leakrate of helium (He) (e.g., leak rate from a device at operatingconditions (e.g., at operating temperature, operating pressure, etc.)filled with He). In some examples, the leak rate of helium (He) can beless than about 1×10⁻⁶ atmospheric cubic centimeters per second (atmcc/s), 5×10⁻⁷ atm cc/s, 1×10⁻⁷ atm cc/s, 5×10⁻⁸ atm cc/s or 1×10⁻⁸ atmcc/s. In some cases, the leak rate of He is equivalent to the total leakrate of He leaving the system (e.g., cell, seal). In other cases, theleak rate of He is the equivalent total He leak rate if one atmosphereof He pressure was placed across the sealed interface, as determinedfrom the actual pressure/concentration differential of He across thesealed interface and the measured He leak rate.

The seal can provide any suitably low helium leak rate. In some cases,the seal provides a helium leak rate of no more than or equal to about1×10⁻¹⁰, 1×10⁻⁹, 1×10⁻⁸, 1×10⁻⁷, 5×10⁻⁷, 1×10⁻⁶, 5×10⁻⁶, 1×10⁻⁵ or5×10⁻⁵ atmosphere-cubic centimeters per second (atm-cc/s) at atemperature (e.g., a storage temperature of the cell, an operatingtemperature of the cell, and/or a temperature of the seal) of greaterthan or equal to about −25° C., 0° C., 25° C., 50° C., 200° C., 350° C.,450° C., 550° C. or 750° C. The seal can provide such helium leak rateswhen the electrochemical cell has been operated (e.g., at ratedcapacity) for a period of, for example, at least about 1 month, 6months, 1 year, 5 years, 10 years, 20 years or more. In some cases, theseal provides such helium leak rates when the electrochemical cell hasbeen operated for at least about 350 charge/discharge cycles (orcycles), 500 cycles, 1,000 cycles, 3,000 cycles, 10,000 cycles, 50,000cycles, 75,000 cycles or 150,000 cycles.

The seal can electrically isolate the conductor from the electricallyconductive housing. The degree of electrical isolation can be quantifiedby measuring the impedance across the seal. In some cases, the impedanceacross the seal is greater than or equal to about 0.05 kilo-Ohms (kOhm),0.1 kOhm, 0.5 kOhm, 1 kOhm, 1.5 kOhm, 2 kOhm, 3 kOhm, 5 kOhm, 10 kOhm,50 kOhm, 100 kOhm, 500 kOhm, 1,000 kOhm, 5,000 kOhm, 10,000 kOhm, 50,000kOhm, 100,000 kOhm or 1,000,000 kOhm at any operating, resting, orstoring temperature. In some cases, the impedance across the seal isless than about 0.1 kOhm, 1 kOhm, 5 kOhm, 10 kOhm, 50 kOhm, 100 kOhm,500 kOhm, 1,000 kOhm, 5,000 kOhm, 10,000 kOhm, 50,000 kOhm, 100,000 kOhmor 1,000,000 kOhm at any operating, resting, or storing temperature. Theseal can provide electrical isolation when the electrochemical cell hasbeen operated (e.g., at rated capacity) for a period of, for example, atleast about 1 month, 6 months, 1 year or more. In some cases, the sealprovides the electrical isolation when the electrochemical cell has beenoperated for at least about 350 charge/discharge cycles (or cycles), 500cycles, 1,000 cycles, 3,000 cycles, 10,000 cycles, 50,000 cycles, 75,000cycles or 150,000 cycles. The seal can provide electrical isolation whenthe electrochemical cell has been operated for a period of at leastabout 1 year, 5 years, 10 years, 20 years, 50 years or 100 years. Insome cases, the seal provides the electrical isolation when theelectrochemical cell has been operated for greater than or equal toabout 350 charge/discharge cycles.

The seal can be durable. In some examples, the seal can maintainintegrity for at least about 1 month, 2 months, 6 months, 1 year, 2years, 5 years, 10 years, 15 years, 20 years or more. The seal can havesuch properties and/or metrics under operating conditions.

In some examples, a battery or device comprising the seal can have aCoulombic efficiency (e.g., measured at a current density of about 20mA/cm², 200 mA/cm² or 2,000 mA/cm²) of at least about 50%, 55%, 60%,65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.8%,99.9% or more. In some examples, a battery or device comprising the sealcan have a DC-DC efficiency (e.g., measured at a current density ofabout 200 mA/cm² or 220 mA/cm²) of at least about 50%, 55%, 60%, 65%,70%, 75%, 80%, 85%, 90%, 95% or more. In some examples, a battery ordevice comprising the seal can have a discharge time (e.g., measured ata current density of about 200 mA/cm² or 220 mA/cm²) of at least about 1hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9hours, 10 hours or more. In some examples, a battery or devicecomprising the seal can have a discharge time (e.g., measured at acurrent density of about 200 mA/cm² or 220 mA/cm²) between about 4 hoursand 6 hours, 2 hours and 6 hours, 4 hours and 8 hours or 1 hour and 10hours. In some examples, a battery or device comprising the seal canhave a capacity fade rate (e.g., discharge capacity fade rate) of lessthan about 10%/cycle, 5%/cycle, 1%/cycle, 0.5%/cycle, 0.1%/cycle,0.08%/cycle, 0.06%/cycle, 0.04%/cycle, 0.02%/cycle, 0.01%/cycle,0.005%/cycle, 0.001%/cycle, 0.0005%/cycle, 0.0002%/cycle, 0.0001%/cycle,0.00001%/cycle or less. The capacity fade rate can provide a measure ofthe change (decrease) in discharge capacity in ‘ 3/0 per cycle’ (e.g.,in % per charge/discharge cycle).

In some cases, the seal allows the electrochemical cell to achieve onone or more given operating conditions (e.g., operating temperature,temperature cycling, voltage, current, internal atmosphere, internalpressure, vibration, etc.). Some examples of operating conditions aredescribed in TABLE 2. Such operating conditions can include, but are notlimited to, metrics such as, for example, operating temperature, idletemperature, temperature cycling, voltage, current, internal atmosphere,external atmosphere, internal pressure, vibration, and lifetime.

TABLE 2 EXAMPLES OF OPERATING CONDITIONS FOR CELLS Item Exampledescription Example metrics Operating The normal temperature 440° C. to550° C. temperature experienced by the seal during operation. Idle Thetemperature experienced −25° C. to temperature by the seal while battery50° C. is idle (e.g., in manufacturing, during transport, battery inoff-mode). Temperature The seal can experience −25° C. to cyclinginfrequent but large amplitude 700° C. with at thermal cycles over thecourse least about 10 of battery operating lifetime. thermal cyclesVoltage The voltage drop across the 0 V to 3 V seal. Current Theelectric current flowing 0 A to 500 A through materials that interfacewith the seal. Internal The seal is exposed to vapors 0.133 Pa or 0.001atmosphere of reactive alkali metals or torr vapor pressure reactivealkaline earth of alkali metals or metals and halide salts from alkalineearth within the battery. metals and halide salts External Theatmosphere that the seal Air at 0° C. to atmosphere is exposed to fromthe 550° C. accompanied externals of the battery, by 100% relative e.g.,ambient air, high humidity moisture. Internal Vacuum gradient orpositive 0.5 atm to 4.0 atm pressure pressure across the seal. VibrationThe seal can be exposed to Capable of handling vibrations caused duringvibrational loading manufacturing, transportation, analogous toinstallation, operation, and transportation when rare events (e.g.,drops, used in cell or shock impact). system application. Lifetime Theexpected lifetime of a 20 year life seal in full operation. with <1%failure

In some examples, an operating temperature (e.g., temperatureexperienced by the seal during operation) is at least about 100° C.,200° C., 300° C., 400° C., 500° C., 600° C., 700° C., 800° C., 900° C.or more. In some examples, the temperature experienced by the sealduring operation is between about 440° C. and 550° C., 475° C. and 550°C., 350° C. and 600° C. or 250° C. and 650° C. In an example, anoperating temperature of about 400° C. to about 500° C., about 450° C.to about 550° C., about 450° C. to about 500° C. or about 500° C. toabout 600° C., or an operating temperature of at least about 200° C.(e.g., suitable for cell chemistries that can operate as low as 200° C.)can be achieved. In some cases, the temperature experienced by the sealmay be about equal to the operating temperature of the electrochemicalcell or high temperature device (e.g., energy storage device). In somecases, the temperature experienced by the seal may differ from theoperating temperature of the electrochemical cell or high temperaturedevice (e.g., by at least, less than or equal to about 1° C., 5° C., 10°C., 20° C., 50° C., 100° C., 150° C., 200° C., and the like). In anexample, an electrochemical cell comprises a reactive materialmaintained at a temperature (e.g., operating temperature of the cell) ofat least about 200° C., and the temperature of the seal is at leastabout 200° C. (e.g., the same as the operating temperature of the cell,or different than the operating temperature of the cell). In some cases,the operating temperature of the seal can be lower or higher than theoperating temperature of the electrochemical cell or high temperaturedevice.

In some examples, an idle temperature (e.g., temperature experienced bythe seal while device (e.g., battery) is idle, such as, for example, inmanufacturing, during transport, device (e.g., battery) in off-mode,etc.) is greater than about −25° C., −10° C., 0° C., 15° C., 20° C. or30° C. In some examples, the idle temperature is less than about 30° C.,20° C., 15° C., 0° C., −10° C., −25° C. or less. In some examples, thetemperature experienced by the seal while the device is idle is betweenabout −25° C. and 50° C.

In some examples, temperature cycling (e.g., infrequent but largeamplitude thermal cycles over the course of device (e.g., battery)operating lifetime that the seal can experience) is over a range of atleast about 100° C., 200° C., 300° C., 400° C., 500° C., 600° C., 700°C., 800° C. or 900° C. In some examples, the temperature cycling is overa range of less than about 100° C., 200° C., 300° C., 400° C., 500° C.,600° C., 700° C., 800° C. or 900° C. In an example, the temperaturecycling is between about −25° C. and 700° C. The seal may withstand(e.g., continue to meet all required specifications) such temperaturecycling after at least about 1 thermal cycle, 5 thermal cycles, 10thermal cycles, 20 thermal cycles, 40 thermal cycles, 80 thermal cycles,100 thermal cycles or 1000 thermal cycles. In some cases, the cell andseal can be thermally cycled at least about 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55,60, 65, 70, 75, 80, 85, 90, 95, 100 or more times per year (e.g., goingfrom room temperature up to operating temperature). The seal may becapable of withstanding brief temperature excursions above or belowtypical operating temperature range limits. For example, the seal may becapable of withstanding temperature excursions for greater than or equalto about 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8hours, 9 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20hours, 22 hours, 24 hours or more. In some cases, such temperatureexcursions may not exceed 700° C.

In some examples, voltage (e.g., voltage drop across the seal) is atleast about 0.1 V, 0.5 volt (V), 1 V, 1.5 V, 2 V, 2.5 V, 3 V, 4 V, 5 V,6 V, 7 V, 8 V, 9 V or 10 V. In some examples, the voltage is less thanabout 0.1 V, 0.5 V, 1 V, 1.5 V, 2 V, 2.5 V, 3 V, 4 V, 5 V, 6 V, 7 V, 8V, 9 V or 10 V. In some examples, the voltage drop across the seal isbetween about 0 V and 3 V or 0 V and 10 V.

In some examples, current (e.g., electric current flowing throughmaterials that interface with the seal) is at least about 0 ampere (A),5 A, 10 A, 25 A, 50 A, 100 A, 150 A, 200 A, 250 A, 300 A, 350 A, 400 A,450 A or 500 A. In some examples, the current is less than about 0 A, 5A, 10 A, 25 A, 50 A, 100 A, 150 A, 200 A, 250 A, 300 A, 350 A, 400 A,450 A or 500 A. In some examples, the electric current flowing throughmaterials that interface with the seal is between about 0 A and 500 A.

In some examples, internal atmosphere (e.g., vapors of reactivematerials, such as, for example, alkali metals or reactive alkalineearth metals and halide salts from within the device (e.g., battery)that the seal is exposed to), comprises at least about 1×10⁻⁵ torr,5×10⁻⁵ torr, 1×10⁴ torr, 5×10⁻⁴ torr, 1×10⁻³ torr, 5×10⁻³ torr, 1×10⁻²torr, 5×10⁻² torr, 1×10⁻¹ torr, 5×10⁻¹ torr or 1 torr vapor pressure ofalkali metals or alkaline earth metals and halide salts. In someexamples, the internal atmosphere comprises less than about 1×10⁻⁵ torr,5×10⁻⁵ torr, 1×10⁻⁴ torr, 5×10⁻⁴ torr, 1×10⁻³ torr, 5×10⁻³ torr, 1×10⁻²torr, 5×10⁻² torr, 1×10⁻¹ torr, 5×10⁻¹ torr or 1 torr vapor pressure ofalkali metals or alkaline earth metals and halide salts. In someexamples, the internal atmosphere that the seal is exposed to comprisesat least about 0.001 torr (about 0.133 Pa) or 0.01 torr (about 1.33 Pa)vapor pressure of alkali metals or alkaline earth metals and halidesalts. In some examples, the internal atmosphere that the seal isexposed to comprises less than about 0.001 torr (about 0.133 Pa) or 0.01torr (about 1.33 Pa) vapor pressure of alkali metals or alkaline earthmetals and halide salts.

The external surface of the cell and seal can be exposed to theatmosphere (e.g., ambient environment comprising O₂, N₂, Ar, CO₂, H₂O).In some examples, external atmosphere (e.g., atmosphere that the seal isexposed to from the externals of the device (e.g., battery) such as, forexample, ambient air, high moisture, etc.) is at a temperature of atleast about 0° C., 50° C., 100° C., 150° C., 200° C., 250° C., 300° C.,350° C., 400° C., 450° C., 500° C., 550° C., 600° C., 700° C., 750° C.,800° C., 850° C. or 900° C. In some examples, the external atmosphere isat a temperature of less than about 0° C., 50° C., 100° C., 150° C.,200° C., 250° C., 300° C., 350° C., 400° C., 450° C., 500° C., 550° C.,600° C., 700° C., 750° C., 800° C., 850° C. or 900° C. In some examples,the atmosphere that the seal is exposed to from the externals of thedevice is at a temperature of between about 0° C. and 550° C., 350° C.and 600° C. or 250° C. and 650° C. (e.g., accompanied by 100% relativehumidity). Such temperatures can be accompanied by greater than or equalto about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100% relativehumidity. For example, such temperatures are accompanied by 100%relative humidity.

In some examples, internal pressure (e.g., vacuum gradient or positivepressure across the seal) can be at least about 0 atm, 0.1 atm, 0.2 atm,0.4 atm, 0.6 atm, 0.8 atm, 1 atm, 1.5 atm, 2 atm, 2.5 atm, 3 atm, 3.5atm, 4 atm or 5 atm. In some examples, the internal pressure can be lessthan about 0 atm, 0.1 atm, 0.2 atm, 0.4 atm, 0.6 atm, 0.8 atm, 1 atm,1.5 atm, 2 atm, 2.5 atm, 3 atm, 3.5 atm, 4 atm or 5 atm. In someexamples, the vacuum gradient or positive pressure across the seal isbetween about 0.5 atm and 4.0 atm.

The seal may be capable of handling vibration (e.g., vibrations causedduring manufacturing, transportation, installation, operation, and rareevents such as, for example, drops or shock impact that the seal can beexposed to). In an example, the seal is capable of handling vibrationalloading analogous to transportation (e.g., when used in a cell or systemapplication).

The seal may have a given lifetime (e.g., expected lifetime of the sealin full operation). In some examples, the lifetime of seal is at leastabout 1 month, 2 months, 6 months, 1 year, 2 years, 5 years, 10 years,15 years, 20 years or more. The seal can have such lifetimes atoperation (e.g., utilization) of at least about 20%, 40%, 60%, 80%, 90%,or full operation. The seal can have such lifetimes at a failure rate ofless than about 75%, 50%, 40%, 40%, 30%, 20%, 15%, 10%, 5%, 1%, 0.1%,0.01% or 0.001%. In an example, the seal has a 20 year life with lessthan about 1% failure, or a 20 year life with less than about 10%failure.

The seal may have a cycle life (e.g., number of completecharge/discharge cycles of the cell that the seal is able to supportbefore its performance degrades and/or before the capacity of theelectrochemical cell/battery/energy storage device falls below, forexample, 80% of its original capacity) of at least about 10, 50, 100,150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1,000,1,500, 2,000, 3000, 5000, 10,000, 20,000, 50,000, 100,000 cycles.

External cell dimensions may impact system design and performance. Forexample, a seal height may be limited to a given distance above a celltop plate (e.g., top surface of the cell container lid). In some cases,seal height can be less than about 2 inches, 1 inch, ½ inch (e.g., sincespacing between cells can change the thermal environment within a stackcell chamber), ¼ inch or ⅛ inch above the cell top plate. In some cases,the resistance of the conductor (e.g., negative current lead) thatconducts electric current from outside the cell through the aperture inthe cell lid is sufficiently low. For example, the resistance of theconductor is sufficiently low to achieve a given system efficiency(e.g., greater than or equal to about 40%, 50%, 60%, 75%, 80%, 90%, 95%or 99% energy efficiency). In some instances, a decreasing diameter orradial circumference of the conductor may allow for a more robust sealto be formed around the conductor, but lead to an increase in resistanceof the conductor. In such instances, the resistance of the conductor canbe decreased or minimized to a value sufficient for a robust seal to beformed (e.g., the resistance of the conductor in the seal can be as lowas possible as long as a robust seal can be made, and the conductor canbe large enough to achieve low resistance but small enough to achieve arobust seal around it). The resistance may be less than about 200milliohms (mOhm), 100 mOhm, 80 mOhm, 50 mOhm, 30 mOhm, 10 mOhm, 3 mOhm,1 mOhm, 0.75 mOhm, 0.5 mOhm, 0.3 mOhm, 0.1 mOhm, 0.075 mOhm, 0.05 mOhm,0.03 mOhm or 0.01 mOhm.

The chemical stability of the materials (e.g., cell lid assemblymaterials, adhesive seal material(s), etc.) can be considered (e.g., toensure the durability of the seal during all possible temperatures thatthe system may reach). The seal may be exposed to one or more differentatmospheres, including the cell internals (internal atmosphere) and openair (external atmosphere). For example, the seal can be exposed totypical air constituents including moisture, as well as to potentiallycorrosive active materials in the cell. In some implementations, ahermetic seal is provided. A hermetically sealed battery or batteryhousing can prevent an unsuitable amount of air, oxygen, nitrogen,and/or water from leaking or otherwise entering into the battery. Ahermetically sealed battery or battery housing can prevent an unsuitableamount of one or more gases surrounding the battery (e.g., air or anycomponent(s) thereof, or another type of surrounding atmosphere or anycomponent(s) thereof) from leaking or otherwise entering into thebattery. In some cases, a hermetically sealed cell or cell housing canprevent gas or metal/salt vapors (e.g., helium, argon, negativeelectrode vapors, electrolyte vapors) from leaking from the cell.

A hermetically sealed battery or battery housing may prevent anunsuitable amount of air, oxygen, nitrogen, and/or water into thebattery (e.g., an amount such that the battery maintains at least about80% of its energy storage capacity and/or maintains a round-tripCoulombic efficiency of at least about 90% per cycle when charged anddischarged at least about 100 mA/cm² for at least about one year, 2years, 5 years, 10 years or 20 years). In some instances, the rate ofoxygen, nitrogen, and/or water vapor transfer into the battery is lessthan about 0.25 milli-liter (mL) per hour, 0.02 mL per hour, 0.002 mLper hour or 0.0002 mL per hour when the battery is contacted with air ata pressure that is at least about (or less than about) 0 atmospheres(atm), 0.1 atm, 0.2 atm, 0.3 atm, 0.4 atm, 0.5 atm, 0.6 atm, 0.7 atm,0.8 atm, 0.9 atm or 0.99 atm higher than, or at least about (or lessthan about) 0.1 atm, 0.2 atm, 0.5 atm or 1 atm lower than the pressureinside the battery and a temperature of between about 400° C. and 700°C. In some instances, the rate of metal vapor, molten salt vapor, orinert gas transfer out of the battery is less than about 0.25 mL perhour, 0.02 mL per hour, 0.002 mL per hour or 0.0002 mL per hour when thebattery is contacted with air at a pressure of greater than or equal toabout 0.5 atm, 1 atm, 1.5 atm, 2 atm, 2.5 atm, 3 atm, 3.5 atm or 4 atmless than the pressure inside the battery and a temperature betweenabout 400° C. and 700° C. In some examples, the number of moles ofoxygen, nitrogen, or water vapor that leaks into the cell over a givenperiod (e.g., at least about a 1 month period, 6 month period, 1 yearperiod, 2 year period, 5 year period, 10 year period or more) is lessthan about 10%, 5%, 3%, 1%, 0.5%, 0.1%, 0.05% or 0.5% of the number ofmoles of active material (e.g., active metal material) in the cell.

The seal can meet one or more specifications, including, but not limitedto: electrically insulating and hermetic, ability to function atoperating temperature for duration of lifespan, thermal cycle-ability,sufficiently high electrical conductivity of the conductor (e.g.,negative current lead), configuration that does not excessively protrudefrom cell body, inner surface chemically stable with liquids and vaporsof active components, outer surface stable in air, ability to avoidarcing under high potentials, etc.

Pressure Relief

A sealed high temperature device containing reactive materials may insome cases experience an increase in internal pressure (e.g., if thetemperature of the device is increased above the boiling point of one ormore of the materials within the device). The device may comprise ametal housing (e.g., stainless steel cell body) and a metal housing lid(e.g., stainless steel cell lid) that are joined (e.g., brazed orwelded) together. The cell lid may comprise a high temperature seal. Inthe event of a pressure build-up inside the device, the device mayrupture. In some cases, the device may rupture, eject material, andresult in a hazardous event. It may be desirable for the device tocomprise a component that relieves pressure before it reaches ahazardous level. It may also be desirable that the pressure reliefcomponent is in a gaseous head space of the device such that thepressure is released via the escape of gaseous components rather thanliquid components.

In some implementations, the seal may be designed to serve as thepressure relief component (e.g., to be the weakest portion of the devicethat will allow the pressure that may build inside the device to bereleased through the seal) above a critical pressure and/or above acritical temperature. One or more seals may be provided on the device(e.g., a seal around a conductor, a dedicated pressure relief seal, aseal around a conductor that also provides pressure relief, etc.). Insome cases, the seal releases pressure when the device and/or seal isheated above the melting point of the braze material that is used tocreate the metal-to-ceramic sealed interfaces. In some cases, thestrength and/or geometry of the ceramic-to-metal joints in the seal aredesigned to fail (e.g., leak) before the metal-to-metal joints of thedevice housing and/or lid (and/or before the metal-to-metal joints ofthe seal). For example, one or more of the ceramic-to-metal brazes inthe seal may be weaker than the metal-to-metal welds of the devicehousing and/or lid. In some examples, the critical pressure inside thedevice can be greater than about 1 atm, 2 atm, 3 atm, 4 atm, 5 atm, 10atm, 20 atm, 50 atm, or 100 atm. In some examples, the criticaltemperature (e.g., of the device and/or of the seal) can be greater thanabout 300° C., 400° C., 500° C., 600° C., 700° C., 800° C., 900° C.,1000° C., 1100° C., 1200° C., 1300° C., or 1400° C.

Materials, Chemical Compatibility and Coefficients of Thermal Expansion

Materials and features of seals herein may be configured to achievesuitable materials (e.g., chemical, mechanical, thermal) compatibility.Materials compatibility may include, for example, suitable matching ofcoefficients of thermal expansion (CTEs), suitable Young's moduluscharacteristics (e.g., low Young's modulus metal materials) and/orsuitable ductility characteristics (e.g., one or more components withhigh ductility). Seals may incorporate structural features that cancompensate for CTE mismatch.

Materials may be selected to achieve low CTE mismatch between various(e.g., pairs of) seal materials and/or housing (e.g., cell lid and/orbody) materials. Materials may be selected to achieve low stress (e.g.,stress due to CTE mismatch) at joint(s) between various (e.g., pairs of)seal materials and/or housing materials. A joint between various sealmaterials and/or housing materials may be of a given type (e.g.,ceramic-to-metal or metal-to-metal). In an example, a ceramic materialhas a CTE that suitably (e.g., substantially) matches a CTE of a celllid or body, thereby decreasing or minimizing stress(es) (e.g.,stress(es) at one or more ceramic-to-metal joint(s) between the ceramicmaterial and the cell lid or body). In another example, a ceramicmaterial has a CTE that is suitably (e.g., substantially) different thanthe CTE of the cell lid or body. In this instance, a metal collar orsleeve that is a better CTE match or has one or more other propertiesthat reduce the ceramic-to-metal joint stress may be used. The metalcollar or sleeve may move the CTE stress from the ceramic joint (e.g.,from the ceramic-to-metal joint between the ceramic and the metal collaror sleeve) to the cell lid or body joint (e.g., to the metal-to-metaljoint between the metal collar or sleeve and the cell lid or body). Theceramic material may have a CTE that suitably (e.g., substantially)matches a CTE of the metal collar or sleeve. The ceramic material mayhave a CTE that is suitably (e.g., substantially) different than the CTEof the metal collar or sleeve. The ceramic-to-metal seal jointstress(es) can be reduced, for example, by using a ductile metal collaror sleeve (e.g., comprising at least about 95% or 99% Ni) and/or byusing a ductile braze material (e.g., comprising at least about 95% or99% Ag, Cu or Ni). The ductile braze material may be used to reducestress(es) at the ceramic-to-metal joint between the ceramic and thecell lid or body or to reduce stress(es) at the ceramic-to-metal jointbetween the ceramic and metal collar or sleeve.

The seal can be made of any suitable material (e.g., such that the sealforms a hermetic seal and an electrical isolation). In some cases, theseal comprises a ceramic material and a braze material. The ceramicmaterial can have a CTE that is matched to the housing material suchthat the electrochemical cell maintains suitable gas-tight and/orelectrically insulating properties during operation and/or start-up ofthe battery. The ceramic material may have a CTE that matches a CTE ofthe braze material and/or the cell top (e.g., lid or cap, or anycomponent of a cell lid assembly) or body. In some cases, the CTEs ofthe ceramic material, braze material and cell top or body may not beidentically matched, but may be sufficiently close to minimize stressesduring the braze operation and subsequent thermal cycles in operation.In some cases, the CTE of the ceramic material may not be sufficientlyclose to the CTE of the cell top or body (e.g., in some cases resultingin an unstable and/or unreliable ceramic-to-metal joint which may loseits leak-tight property). The seal can comprise a collar (e.g., a thinmetal collar) or sleeve (e.g., to overcome the CTE mismatch between aceramic material and the cell lid or cell body). The collar or sleevecan be a metal collar or sleeve. The collar or sleeve can be brazed tothe ceramic (e.g., via a braze material) and joined to the cell lidand/or the negative current lead that protrudes through the cell lid andinto the cell cavity. A suitable collar or sleeve material may beselected in order to reduce the resulting stresses at theceramic-to-metal joint (e.g., by reducing the CTE mismatch), increasethe resulting stress at the collar or sleeve-to-cell lid or body joint(e.g., by increasing the CTE mismatch), or a combination thereof. Theseal can comprise features that alleviate CTE mismatches between theceramic and the cell lid and/or the negative current lead. Any aspectsof the disclosure described in relation to the cell top or body (e.g.,CTE, joint stress, configuration and/or formation, etc.) may equallyapply to the cell top and body at least in some configurations. Anyaspects of the disclosure described in relation to the cell top mayequally apply to the cell body at least in some configurations, and viceversa.

Materials herein may have temperature-dependent properties. Suchproperties may include, for example, CTE and/or yield strength. Forexample, the CTE of a material may be measured across a given (e.g.,specified) temperature range. Thus, a material may have one CTE valueover the range of, for example, 20° C. to 200° C. (e.g., 10 ppm/K), andanother CTE value over the range of, for example, 20° C. to 400° C.(e.g., 12 ppm/K). Such properties may or may not change continuouslywith temperature (e.g., the CTE may be a continuous function withtemperature). In another example, yield strength may be a function oftemperature. Values of the yield strength of materials herein (e.g., ofa metal collar or sleeve material) may be provided at one or moretemperatures at or below braze temperature (e.g., at about 1100° C. orlower for some metal collar or sleeve materials). Values oftemperature-dependent properties herein may be taken to be at anyrelevant temperature or range. Features and characteristics such as, forexample, CTE mismatch may in some cases vary with temperature. Values ofCTE mismatch herein may apply at any temperature, or at a giventemperature or range of temperatures (e.g., the values may be maximumvalues, values at a steady-state operating temperature, average valuesfrom room temperature up to operating temperature, etc.).

The CTE of the ceramic material may be at least about 3 microns permeter per degree Celsius (μm/m/° C., same as parts per million perdegree Kelvin (ppm/K)), 4 μm/m/° C., 5 μm/m/° C., 6 μm/m/° C., 7 μm/m/°C., 8 μm/m/° C., 9 μm/m/° C., 10 μm/m/° C., 11 μm/m/° C., 12 μm/m/° C.,13 μm/m/° C. or 14 μm/m/° C. The CTE of the ceramic material may be lessthan or equal to about 3 μm/m/° C., 4 μm/m/° C., 5 μm/m/° C., 6 μm/m/°C., 7 μm/m/° C., 8 μm/m/° C., 9 μm/m/° C., 10 μm/m/° C., 11 μm/m/° C.,12 μm/m/° C., 13 μm/m/° C. or 14 μm/m/° C. The CTE of the ceramicmaterial may be between about 4 μm/m/° C. and 14 μm/m/° C., 6 μm/m/° C.and 13 μm/m/° C., or 8 μm/m/° C. and 11 μm/m/° C. In some cases, theceramic material comprises at least about 50% AlN and has a CTE of lessthan about 5 μm/m/° C. In some cases, the ceramic material comprises atleast about 50% neodymium oxide (Nd₂O₃), lanthanum oxide (La₂O₃) orcerium oxide (CeO₂) and has a CTE of greater than about 8 μm/m/° C., 9μm/m/° C., 10 μm/m/° C., 11 μm/m/° C. or 12 μm/m/° C. The ceramicmaterial may have such CTE values for a temperature range of, forexample, between about 25° C. and 400° C., 20° C. and 500° C., 25° C.and 500° C., 25° C. and 600° C., 25° C. and 900° C., or 25° C. and 1000°C.

The CTE of the metal collar or sleeve may be at least about 5 μm/m/° C.,6 μm/m/° C., 7 μm/m/° C., 8 μm/m/° C., 9 μm/m/° C., 10 μm/m/° C., 11μm/m/° C., 12 μm/m/° C., 13 μm/m/° C., 14 μm/m/° C., 15 μm/m/° C., 16μm/m/° C., 17 μm/m/° C., 18 μm/m/° C., 19 μm/m/° C. or 20 μm/m/° C. TheCTE of the metal collar or sleeve may be less than or equal to about 20μm/m/° C., 19 μm/m/° C., 18 μm/m/° C., 17 μm/m/° C., 16 μm/m/° C., 15μm/m/° C., 14 μm/m/° C., 13 μm/m/° C., 12 μm/m/° C., 11 μm/m/° C., 10μm/m/° C., 9 μm/m/° C., 8 μm/m/° C., 7 μm/m/° C., 6 μm/m/° C. or 5μm/m/° C. In some cases, the metal collar or sleeve comprises Zr and hasa CTE of less than or equal to about 7 μm/m/° C. In some cases, themetal collar or sleeve comprises Ni (e.g., at least about 95% or 99% Ni,or at least about 40% Ni and at least about 40% Fe by weight) and has aCTE of greater than or equal to about 6 μm/m/° C., 7 μm/m/° C., 8 μm/m/°C., 9 μm/m/° C., 10 μm/m/° C., 11 μm/m/° C., 12 μm/m/° C., 13 μm/m/° C.,14 μm/m/° C., 15 μm/m/° C., 16 μm/m/° C., 17 μm/m/° C., 18 μm/m/° C., 19μm/m/° C. or 20 μm/m/° C. The metal collar or sleeve may comprisegreater than or equal to about 5%, 10%, 15%, 20%, 25%, 30%, 31%, 32%,33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%,47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%,65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% Ni (e.g., by weight). The metalcollar or sleeve may comprise such Ni compositions in combination withgreater than or equal to about 5%, 10%, 15%, 20%, 25%, 30%, 31%, 32%,33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%,47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%,65%, 70%, 75%, 80%, 85%, 90%, 95% or 99% Fe (e.g., by weight). Such Nior Ni—Fe compositions (e.g., alloys) may comprise one or more otherelements (e.g., C, Co, Mn, P, S, Si, Cr and/or Al) with individualconcentrations or a total concentration of less than or equal to about1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.15%, 0.1%, 0.09%, 0.08%,0.07%, 0.06%, 0.05%, 0.04%, 0.03%, 0.025%, 0.01% or 0.005%. In somecases, the metal collar or sleeve comprises greater than or equal toabout 50.5% Ni, greater than or equal to about 48% Fe, and less than orequal to about 0.60% Mn, 0.30% Si, 0.005% C, 0.25% Cr, 0.10% Co, 0.025%P and/or 0.025% S (e.g., alloy 52). In some cases, the metal collar orsleeve comprises greater than or equal to about 41% Ni, greater than orequal to about 58% Fe, and less than or equal to about 0.05% C, 0.80%Mn, 0.40% P, 0.025% S, 0.30% Si, 0.250% Cr and/or 0.10% Al (e.g., alloy42). In some cases, the metal collar or sleeve comprises an Fe alloywith between about 17.5% and 19.5% Cr, between about 0.10% and 0.50% Ti,between about 0.5% and 0.90% niobium, less than or equal to about 1% Ni,1% Si, 1% Mn, 0.04% phosphorus, 0.03% nitrogen, 0.03% sulfur and/or0.03% carbon, and a balance of Fe (e.g., 18CrCb ferritic stainlesssteel). Such Fe alloy (e.g., 18CrCb ferritic stainless steel) may have aCTE of about 8 ppm/K, 9 ppm/K, 10 ppm/K, 11 ppm/K or 12 ppm/K. In somecases, the metal collar or sleeve comprises an Fe alloy with betweenabout 17.5% and 18.5% Cr, between about 0.10% and 0.60% Ti, betweenabout 0.3% and 0.90% niobium, less than about 1% Si, 1% Mn, 0.04%phosphorus, 0.015% sulfur and/or 0.03% carbon, and a balance of Fe(e.g., grade 441 stainless steel). Such Fe alloy (e.g., 441 stainlesssteel) may have a CTE of about 9 ppm/K, 10 ppm/K, 11 ppm/K, 12 ppm/K, 13ppm/K or 14 ppm/K. In some cases, the metal collar or sleeve comprises aNi alloy with at least about 72% Ni, between about 14% and 17% Cr,between about 6% and 10% Fe, and less than about 0.15% C, 1% Mn, 0.015%S, 0.50% Si and/or 0.5% Cu (e.g., Inconel 600). Such Ni alloy (e.g.,Inconel 600) may have a CTE of about 12 ppm/K, 13 ppm/K, 14 ppm/K, 15ppm/K, 16 ppm/K or 17 ppm/K. In some cases, the metal collar or sleevecomprises a Ni alloy with less than about 0.05% C, 0.25% Mn and/or0.002% S, less than or equal to about 0.20% Si, 15.5% Cr, 8% Fe and/or0.1% Cu, and a balance of Ni and Co (e.g., ATI alloy 600). Such Ni alloy(e.g., ATI alloy 600) may have a CTE of about 12 ppm/K, 13 ppm/K, 14ppm/K, 15 ppm/K, 16 ppm/K or 17 ppm/K. In some cases, the metal collaror sleeve comprises greater than or equal to about 67% Ni, less thanabout 2% Co, 0.02% C, 0.015% B, 0.35% Cu, 1.0% W, 0.020% P and/or 0.015%S, between about 14.5% and 17% Cr, between about 14% and 16.5% Mo,between about 0.2% and 0.75% Si, between about 0.30% and 1.0% Mn,between about 0.10% and 0.50% Al, between about 0.01% and 0.10% La, andless than or equal to about 3% Fe (e.g., Hastelloy S). Such alloy (e.g.,Hastelloy S) may have a CTE of about 12 ppm/K, 13 ppm/K, 14 ppm/K, 15ppm/K, 16 ppm/K or 17 ppm/K. The metal collar or sleeve may have theaforementioned CTE values for a temperature range of, for example,between about 25° C. and 400° C., 20° C. and 500° C., 25° C. and 500°C., 25° C. and 600° C., 25° C. and 900° C., or 25° C. and 1000° C.

The seal may comprise one or more braze materials (e.g., same ordifferent braze materials at different joints when using a metal collaror sleeve, or one braze material when the joining the ceramic materialdirectly to the cell lid or body). The CTE of a braze material may be atleast about 3 microns per meter per degree Celsius (μm/m/° C.), 4 μm/m/°C., 5 μm/m/° C., 6 μm/m/° C., 7 μm/m/° C., 8 μm/m/° C., 9 μm/m/° C., 10μm/m/° C., 11 μm/m/° C., 12 μm/m/° C., 13 μm/m/° C., 14 μm/m/° C., 15μm/m/° C., 16 μm/m/° C., 17 μm/m/° C., 18 μm/m/° C., 19 μm/m/° C. or 20μm/m/° C. The CTE of the braze material may be less than or equal toabout 3 microns per meter per degree Celsius (μm/m/° C.), 4 μm/m/° C., 5μm/m/° C., 6 μm/m/° C., 7 μm/m/° C., 8 μm/m/° C., 9 μm/m/° C., 10 μm/m/°C., 11 μm/m/° C., 12 μm/m/° C., 13 μm/m/° C., 14 μm/m/° C., 15 μm/m/°C., 16 μm/m/° C., 17 μm/m/° C., 18 μm/m/° C., 19 μm/m/° C. or 20 μm/m/°C. The braze material may have such CTE values for a temperature rangeof, for example, between about 25° C. and 400° C., 20° C. and 500° C.,25° C. and 500° C., 25° C. and 600° C., 25° C. and 900° C., or 25° C.and 1000° C.

The stress(es) at the ceramic-to-metal joint may be reduced by brazingthe ceramic to a metal with a suitably (e.g., sufficiently) low yieldstrength. By creating a joint between a strong ceramic and a metal(e.g., metal collar or sleeve) with sufficiently low strength, stressesgenerated at the ceramic-to-metal braze joint may be released byplastically deforming the metal rather than the cracking the ceramic. Insome cases, the ductile metal collar or sleeve comprises a Ni alloycomprising greater than or equal to about 95% or 99% (e.g., greater thanor equal to about 95 wt %, or greater than or equal to about 99 wt %)Ni. The Ni alloy may also comprise less than or equal to about 0.25% Cu,0.35% Mn and/or 0.40% Fe. The metal collar or sleeve may comprise anysuitably ductile metal material described herein. In some cases, a yieldstrength of the metal collar or sleeve is less than or equal to about 50MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa,300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa,900 MPa or 1000 MPa. The metal collar or sleeve may have such yieldstrengths at a temperature of, for example, greater than or equal toabout 25° C., 400° C., 500° C., 600° C., 700° C., 800° C., 900° C.,1000° C. or 1100° C. For example, a metal collar or sleeve can have ayield strength of less than or equal to about 350 MPa at a temperatureof greater than or equal to about 500° C.

The stress(es) at the ceramic-to-metal joint may be reduced by using abraze material that is suitably (e.g., sufficiently) ductile. A ductilebraze material may comprise silver (Ag), copper (Cu) and/or nickel (Ni).The braze material may comprise, for example, at least about 95% or 99%Ag (e.g., by weight), at least about 95% or 99% Cu (e.g., by weight) orat least about 95% or 99% Ni (e.g., by weight). The braze material maycomprise any suitably ductile braze material described herein. Theductile braze material may have a yield strength of less than or equalto about 10 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa,90 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa,450 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa, 900 MPa or 1000 MPa. Thebraze material may have such yield strengths at a temperature of, forexample, greater than or equal to about 25° C., 400° C., 500° C., 600°C., 700° C., 800° C., 900° C., 1000° C. or 1100° C. In some cases, brazematerials may be coated (e.g., Ni coated).

The seal may comprise one or more metallization materials (e.g.,metallization powders). The CTE of a metallization material (e.g., afterthe metallization layer is formed) may be at least about 3 μm/m/° C., 4μm/m/° C., 5 μm/m/° C., 6 μm/m/° C., 7 μm/m/° C., 8 μm/m/° C., 9 μm/m/°C., 10 μm/m/° C., 11 μm/m/° C., 12 μm/m/° C., 13 μm/m/° C., 14 μm/m/°C., 15 μm/m/° C., 16 μm/m/° C., 17 μm/m/° C., 18 μm/m/° C., 19 μm/m/° C.or 20 μm/m/° C. The CTE of the metallization material (e.g., after themetallization layer is formed) may be less than or equal to about 3microns per meter per degree Celsius (μm/m/° C.), 4 μm/m/° C., 5 μm/m/°C., 6 μm/m/° C., 7 μm/m/° C., 8 μm/m/° C., 9 μm/m/° C., 10 μm/m/° C., 11μm/m/° C., 12 μm/m/° C., 13 μm/m/° C., 14 μm/m/° C., 15 μm/m/° C., 16μm/m/° C., 17 μm/m/° C., 18 μm/m/° C., 19 μm/m/° C. or 20 μm/m/° C. Themetallization material may have such CTE values for a temperature rangeof, for example, between about 25° C. and 400° C., 20° C. and 500° C.,25° C. and 500° C., 25° C. and 600° C., 25° C. and 900° C., or 25° C.and 1000° C. The Young's modulus of a metallization material may be lessthan about 50 giga-Pascals (GPa), 75 GPa, 100 GPa, 150 GPa or 500 GPa.The metallization material may have such Young's modulus values for atemperature of, for example, 25° C., 300° C., 400° C., 500° C., 600° C.,900° C., or 1000° C. The metallization material may be chemically stablein air and/or when exposed to reactive materials in the device at atemperature of greater than or equal to about 200° C., 300° C., 400° C.,500° C., 600° C., 900° C., or 1000° C.

In some cases, the maximum difference in CTE (e.g., between any two (ormore) of the ceramic material, metallization material, braze material,metal collar or sleeve, and cell top or body) can be less than about0.01 microns per meter per degree Celsius (μm/m/° C.), 0.02 μm/m/° C.,0.05 μm/m/° C., 0.1 μm/m/° C., 0.2 μm/m/° C., 0.3 μm/m/° C., 0.5 μm/m/°C., 0.75 μm/m/° C., 1 μm/m/° C., 2 μm/m/° C., 3 μm/m/° C., 5 μm/m/° C.,7 μm/m/° C., 10 μm/m/° C. or 15 μm/m/° C. For example, a metal collar orsleeve (e.g., comprising a Ni—Fe alloy such as, for example, alloy 42,alloy 52, 18CrCb ferritic stainless steel, ATI alloy 600 or Hastelloy S)may have a CTE that suitably matches (e.g., within less than about 3μm/m/° C., or within less than about 1 μm/m/° C.) the CTE of the ceramic(e.g., comprising an Nd₂O₃ ceramic such as, for example, Nd₂O₃ with 5%Y₂O₃ and 5% SiC). In some cases, a difference in CTE (e.g., between anytwo (or more) of the ceramic material, braze material, metal collar orsleeve, and cell top or body) can be greater than or equal to about 0.01microns per meter per degree Celsius (μm/m/° C.), 0.02 μm/m/° C., 0.05μm/m/° C., 0.1 μm/m/° C., 0.2 μm/m/° C., 0.3 μm/m/° C., 0.5 μm/m/° C.,0.75 μm/m/° C., 1 μm/m/° C., 2 μm/m/° C., 3 μm/m/° C., 5 μm/m/° C., 7μm/m/° C., 10 μm/m/° C. or 15 μm/m/° C. For example, a braze material(e.g., ductile braze material) may have a CTE that is suitably (e.g., atleast about 1 μm/m/° C.) different than the CTE of the ceramic.

The seal may comprise a ceramic material and a braze material. In somecases, the ceramic material is stable (e.g., thermodynamically stable)when in contact with (e.g., does not chemically react with) one or morereactive materials (e.g., reactive liquid metals or reactive liquidmetal vapors such as, for example, molten lithium or lithium vapor). Insome cases, the ceramic material (e.g., Nd₂O₃) is stable when in contactwith air (or any other type of external atmosphere). In some cases, theceramic material is stable with, is not substantially attacked by (e.g.,the material may have a slight surface reaction, but does not progressinto degradation or attack of the bulk of the material) and does notsubstantially dissolve into the molten salt. Examples of ceramicmaterials include, but are not limited to, aluminum nitride (AlN),beryllium nitride (Be₃N₂), boron nitride (BN), calcium nitride (Ca₃N₂),silicon nitride (Si₃N₄), aluminum oxide (Al₂O₃), beryllium oxide (BeO),calcium oxide (CaO), cerium oxide (CeO₂ or Ce₂O₃), erbium oxide (Er₂O₃),lanthanum oxide (La₂O₃), magnesium oxide (MgO), neodymium oxide (Nd₂O₃),samarium oxide (Sm₂O₃), scandium oxide (Sc₂O₃), ytterbium oxide (Yb₂O₃),yttrium oxide (Y₂O₃), zirconium oxide (ZrO₂), yttria partiallystabilized zirconia (YPSZ), boron carbide (B₄C), silicon carbide (SiC),titanium carbide (TiC), zirconium carbide (ZrC), titanium diboride(TiB₂), chalcogenides, quartz, glass, or any combination thereof. Theceramic material may be electrically insulating (e.g., the ceramicmaterial may have a resistivity greater than about 10² Ohm-cm, 10⁴Ohm-cm, 10⁶ Ohm-cm, 10⁸ Ohm-cm, 10¹⁰ Ohm-cm, 10¹² Ohm-cm, 10¹⁴ Ohm-cm or10¹⁶ Ohm-cm). The ceramic material may have a CTE that is (e.g.,substantially) similar to (e.g., less than or equal to about 0.1%, 0.5%,1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%,45% or 50% different than) a CTE of stainless steel (e.g., grade 430stainless steel, 441 stainless steel or 18CrCb ferritic stainless steel)or nickel alloy (e.g., an alloy comprising greater than or equal toabout 50% Ni and greater than or equal to about 48% Fe, such as, forexample, alloy 52). In an example, a ceramic material comprising Nd₂O₃has a CTE (e.g., at least about 9 μm/m/° C., such as, for example,between about 9 μm/m/° C. and about 10 μm/m/° C.) that substantiallymatches (e.g., within less than about 5%, 10%, 20%, 40%, 60% or 80%) theCTE of a metal collar or sleeve that comprises Fe and/or Ni (e.g., ametal collar or sleeve that comprises one or more alloys describedelsewhere herein, such as, for example, alloy 52, 18CrCb ferriticstainless steel, 441 stainless steel, Inconel 600, ATI alloy 600 orHastelloy S). The ceramic material may be selected, for example, basedon stability, corresponding material set, cost (e.g., Nd₂O₃ may in somecases be lower cost than AlN), electrical and mechanical properties,etc. The ceramic material may comprise a mixture of materials ofdifferent composition and/or morphology, as described in greater detailelsewhere herein (e.g., primary and secondary ceramic materials). Theceramic material may comprise one or more materials that have only onestable charged oxidation state. For example, the materials included inthe ceramics (e.g., included in the overall ceramic material, orincluded in primary or secondary material(s) individually) may onlyexist in one stable charged oxidation state (e.g., Nd₂O₃).

In some cases, the braze material comprises one or more brazeconstituents such that at least one braze constituent has low solubilityin the reactive material, the reactive material has low solubility in atleast one braze constituent, at least one braze constituent does notreact (e.g., form intermetallic alloys with) the reactive material atthe operating temperature of the device, and/or the braze material meltsabove the operating temperature of the device. The reactive material canbe, for example, a reactive metal. In some examples, the braze materialcomprises at least one braze constituent that has low solubility in thereactive metal. In some examples, the reactive metal has low solubilityin the braze constituent. In some examples, the braze constituent doesnot form intermetallic alloys with the reactive metal at the operatingtemperature of the device. In some examples, the braze constituentand/or braze material melts above the operating temperature of thedevice. In some examples, the braze constituent(s) may include Ti, Ni,Y, Re, Cr, Zr, and/or Fe and the reactive metal may include lithium(Li).

Examples of braze constituent materials include, but are not limited to,aluminum (Al), beryllium (Be), copper (Cu), chromium (Cr), iron (Fe),manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), rubidium(Rb), scandium (Sc), silver (Ag), tantalum (Ta), rhenium (Re), titanium(Ti), vanadium (V), yttrium (Y), zirconium (Zr), phosphorus (P), boron(B), carbon (C), silicon (Si), or any combination thereof. In someinstances, the ceramic material comprises aluminum nitride (AlN) and thebraze material comprises titanium (Ti). In some cases, the brazematerial comprises a mixture of two or more materials (e.g., 3materials). The materials may be provided in any proportion. Forexample, the braze can comprise 3 materials at a ratio (e.g., inweight-%, atomic-%, mol-% or volume-%) of about 30:30:40 or 40:40:20. Insome cases, the braze material comprises a mixture of Ti—Ni—Zr. In someinstances, the braze comprises at least about 20, 30 or 40 weight-%titanium, at least about 20, 30% or 40 weight-% nickel, and at leastabout 20, 30, 40, 50 or 60 weight-% zirconium. In some instances, thebraze comprises less than about 20, 30 or 40 weight-% titanium, lessthan about 20, 30% or 40 weight-% nickel, and less than about 20, 30,40, 50 or 60 weight-% zirconium. In some instances, the braze comprisesabout 18% Ti, about 60% Zr, about 22% Ni (e.g., on a weight-%, atomic-%,mol-% or volume-% basis). In some instances, the braze comprises about7% Ti, about 67% Zr, and about 26% Ni (e.g., on a weight-%, atomic-%,mol-% or volume-% basis). In some instances, the braze comprises atleast about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,80, 85, 90, 95 or more weight-%, atomic-%, mol-% or volume-% oftitanium, nickel or zirconium (or any other braze material herein). Insome instances, the braze comprises less than or equal to about 5, 10,15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 ormore weight-%, atomic-%, mol-% or volume-% of titanium, nickel orzirconium (or any other braze material herein). In some instances, thebraze comprises greater than or equal to about 82% Ni, and less than orequal to about 7% Cr, 3% Fe, 4.5% Si, 3.2% B and/or 0.06% C (e.g., BNi-2braze). In some instances, the braze comprises greater than or equal toabout 82% Ni, and less than or equal to about 15% Cr, 4.0% B and/or0.06% C (e.g., BNi-9 braze). In some instances, the braze comprisesgreater than or equal to about 82% Ni, and less than or equal to about15% Cr, 7.3% Si, 0.06% C and/or 1.4% B (e.g., BNi-5b braze). In someinstances, the braze comprises yttrium, chromium or rhenium, and nickel.

To facilitate the use of certain braze materials (e.g., non-active brazematerials) to bond the ceramic material to a metal collar or sleeve, alayer comprising metal (also “metallization layer” and“pre-metallization layer” herein) may first be applied to the ceramicmaterial via a pre-metallization step (e.g., the metallization layer maybe applied to the ceramic material by a coating process). For example, ametallization layer with a controlled layer thickness may be appliedonto the ceramic material by sputter-coating or by vacuum or controlledatmosphere (e.g., Ar or N₂ with H₂ gas) high temperature thermaltreatment (e.g., sintering the metallization layer onto the ceramic)without bonding a metal collar or sleeve to the braze material. Thepre-metallization step may enable, for example, a subsequent brazingstep to bond the pre-metallized ceramic surface to a metal collar orsleeve by using a preferred braze material that may not bond to theceramic material directly (e.g., the braze material may not bond to theceramic material without a metallization layer).

A metallization layer may comprise metallization material (also“pre-metallization material” herein). As described in greater detailelsewhere herein, the metallization material may include one or moremetal and/or non-metal materials (e.g., one or more metals, ceramics,silicon oxide glass, etc.). Application of a metallization material mayresult in formation of one or more layers of the pre-metallizationlayer. The sublayer(s) may be formed in one step (e.g., a processingstep using a single metallization material may result in the formationof two sublayers) or may result from multiple processing steps (e.g.,multiple processing steps using different metallization materials). Ametallization material may include a braze material. For example, atleast a portion (e.g., some portion) of the braze material (e.g.,yttrium, titanium or aluminum) may be applied as metallization materialvia a pre-metallization step. In some instances, a pre-metallizationmaterial may be referred to as a pre-metallization braze material. Themetallization material may be different from a braze material. In someinstances, a material may be referred to as a metallization materialinstead of a braze material. For example, when applying a metal coatingas a powder and bonding that powder to the ceramic, the powder may bereferred to as a metallization powder rather than a braze powder. Suchnomenclature may distinguish between a braze material that may meltduring a thermal process onto the ceramic and/or metal, and ametallization material (e.g., powder) that may effectively sinter ontothe ceramic during a thermal process and may not melt (e.g., may notfully melt) during the thermal process.

At least a portion of the metallization material (e.g., yttrium,titanium or aluminum) applied via the pre-metallization step may beapplied onto the ceramic via sputtering and subsequently covered by alayer of a material that is stable in air (e.g., Cr, Re or Ni) up to andbeyond a given (e.g., intended or certified) operating temperature ofthe seal and/or the cell comprising the seal (e.g., temperatures rangingfrom room temperature to within about 5%, 10%, 20%, 30%, 50% or more ofthe intended operating temperature). The pre-metallization materialapplication process may occur in stages, resulting in a layeredstructure comprising a first layer (e.g., an active layer) adjacent tothe ceramic and a second layer (e.g., a protective layer) that coversthe first layer. The second layer may be applied to the first layerusing the same coating process (e.g., a sputter-coated thin layer of Ymay be covered with a protective layer of Cr or Re in the samesputtering process step) or via a separate coating process (e.g., adifferent coating process such as, for example, Ni-plating). The activelayer may comprise a metal (e.g., yttrium or titanium) that is capableof thermodynamically reducing the metal constituent in the ceramic(e.g., Nd₂O₃+2Y→Y₂O₃+2Nd, or AlN+Ti→TiN+Al). The protective layer maycomprise a metal (e.g., Ni, Re, Cr, Si or Al), a high temperature metalalloy, a non-metal (e.g., Al₂O₃, SiO₂, MgO, AlN or another stableceramic material), or any combination thereof. The resultingpre-metallized ceramic may comprise an assembly comprising a bulkceramic component and a metallization layer (e.g., a thin layer ofmetallization material). The resulting pre-metallized ceramic maycomprise, for example, an assembly comprising a bulk ceramic component,a thin layer of an active braze material (also “active layer” herein),and/or a thin layer of a protective material (also “protective layer”herein) that covers the active layer. The resulting pre-metallizedceramic may then be brazed (e.g., vacuum-brazed or hydrogenatmosphere-brazed) to a metal collar or sleeve (e.g., collar or sleevecomprising stainless steel) using a pre-metallized-ceramic-to-metalbraze (e.g., Ni-based, Al-based or Cu-based braze), forming a thirdlayer (e.g., pre-metallized-ceramic-to-metal layer). If the protectivelayer is a metal, the metal may be selected such that it forms none or asmall number (e.g., less than or equal to 1, 2 or 3) of intermetalliccompounds (e.g., brittle intermetallic compounds) with the active layerand/or with the pre-metallized-ceramic-to-metal-collar/sleeve brazelayer (also “pre-metallized-ceramic-to-metal layer” herein). The metalmay be selected such that it does not form intermetallic compounds(e.g., brittle intermetallic compounds) with the active layer and/orwith the pre-metallized-ceramic-to-metal-collar/sleeve braze layer. Forexample, using Re or Cr as the protective layer may result inmetal-to-metal interfaces that include none or at most one (e.g.,brittle) intermetallic compound (e.g., Cr may not form intermetalliccompounds with Y or Ni, and Re may not form intermetallic compounds withNi and may only form one intermetallic compound with Y). The protectivelayer may be selected based on its stability in air at the operatingtemperature of the seal and/or its stability when in the presence of(e.g., in contact with) the reactive material (e.g., reactive metal)contained within the housing. In an example, a braze joint comprises alayered structure with a bulk ceramic comprising Nd₂O₃ ceramic, a thin(e.g., sputter-coated or applied via yttrium hydride (YH₃)) layercomprising yttrium metal, a thin (e.g., sputter-coated) layer comprisingchromium or rhenium, a layer comprising nickel and/or copper (e.g.,applied via a brazing process that joins the chromium or rhenium layerto a metal collar or sleeve), and a metal collar or sleeve comprisingstainless steel, nickel or nickel alloys. The layer adjacent to themetal collar or sleeve may comprise greater than or equal to about 10%,20%, 30%, 40%, 50%, 60%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%,88%, 90%, 92%, 94%, 96%, 98% or 99% Ni (e.g., by weight). The layeradjacent to the metal collar or sleeve may comprise such Ni compositionsin combination with one or more other elements (e.g., Cr, Fe, Si, Band/or C) with individual concentrations or a total concentration ofless than or equal to about 20%, 17.5%, 15%, 12.5%, 10%, 9%, 8%, 7%, 6%,5%, 4.5%, 4%, 3.6%, 3.2%, 3%, 2%, 1%, 0.08%, 0.05% or 0.01% (e.g., byweight). The layer adjacent to the metal collar or sleeve may comprisegreater than or equal to about 82% Ni (e.g., BNi-2 braze, BNi-5b brazeor BNi-9 braze). The layer adjacent to the metal collar or sleeve maycomprise a braze alloy with greater than about 30% Ti, 30% Cu, 90% Cu,30% Al, 30% Ag or 80% Ag. A seal comprising copper may comprise a thinlayer of Ni that is plated or applied to the exposed braze (e.g.,copper) surfaces.

A pre-metallization layer (also “metallization layer” herein) may beapplied by bonding (e.g., sintering, at least partially melting and/orotherwise joining) a metallization material (e.g., metallization powder)onto the surface of the ceramic material. The pre-metallization layermay comprise one or more layers (e.g., one or more sublayers, such as,for example, an active layer and a protective layer), and/or one or moreconstituents. In some cases, the pre-metallization layer can compriseseparate active and protective layers. In some cases, the active layercan simultaneously be a protective layer (e.g., a separate protectivelayer may not be needed). A protective layer may or may not beconsidered part of the pre-metallization layer. The metallizationmaterial may comprise metal powder. The metal metallization powder maycomprise one or more metals including, for example, manganese,molybdenum, tungsten, niobium, and/or tantalum. The metallizationmaterial (e.g., metallization powder) may comprise metal powder mixedwith one or more other materials (e.g., polymers, organic dispersants,water-based solvents, ceramics, glass, or any combination thereof) toform a slurry or paint that can be applied to the ceramic (e.g., priorto melting). In an example, the ceramic material (e.g., AlN or Nd₂O₃)may be bonded to a layer of metallization powder comprising tungstenparticles by heating to at least about 1000° C., 1200° C., 1400° C.,1600° C., 1800° C. or 2000° C. The bonding may include sintering. Thebonding may include at least partially melting one or more components ofthe metallization material (e.g., thereby aiding the sintering). Forexample, in some Mo—Mn metallization powders that comprise mostly Mo,the Mn may form some liquid phase during the metallization process andthen constitutionally freeze and alloy with Mo, thus partially meltingthe metallization powder during the process. Partially melting themetallization powder in this way may aid in fully sintering themetallization layer onto the ceramic. Other examples of Mo—Mnmetallization powders may include low melting point alloys; such alloysmay or may not be suitable as metallization powders. After bonding themetallization powder to the ceramic, the metallization layer (e.g.,tungsten (W)) may be plated with nickel. In another example, themetallization powder (e.g., manganese (Mn) and/or molybdenum (Mo)) maybe bonded (e.g., sintered, at least partially melted), for example, nearor above (e.g., at greater than or equal to) about 1330° C., 1400° C.,1500° C., 1550° C. or 1600° C. After the metallization powder is bondedto the ceramic material, it may be coated or plated with Ni to decreaseor prevent corrosion or oxidation.

The metallization layer may comprise one or more primary metalconstituents that may be chosen based on a CTE that closely matches aceramic material (e.g., Nd₂O₃), a low Young's modulus, stability in airat elevated (e.g., operating) temperatures, or any combination thereof.In some examples, a difference between a CTE of the ceramic material anda CTE of the primary metallization metal constituent may be less than orequal to about 3 ppm/K, 2 ppm/K, 1.5 ppm/K, 1 ppm/K, 0.5 ppm/K, 0.25ppm/K, 0.1 ppm/K or 0.025 ppm/K. In some examples, a CTE of a primarymetallization metal constituent may be less than or equal to about 6.5ppm/K, 7 ppm/K, 7.5 ppm/K, 8 ppm/K, 8.5 ppm/K, 9 ppm/K, 9.5 ppm/K, 10ppm/K, 10.5 ppm/K, 11 ppm/K, 11.5 ppm/K or 12 ppm/K. The CTEs may be fora temperature range of, for example, between about 20° C. and 1000° C.,or 20° C. and 500° C. A primary metallization metal constituent may haveor be chosen based on a low Young's modulus value. A primarymetallization metal constituent may have or be chosen based on a Young'smodulus value of, for example, less than about 200 giga-Pascals (GPa),150 GPa, 100 GPa, 75 GPa or 50 GPa. The primary metallization metalconstituent may be, for example, niobium (Nb) or tantalum (Ta). Themetallization material may also include one or more secondarymetallization metals. The secondary metallization metals may improvephysical, thermal, chemical and/or mechanical properties, such as, forexample, stability in air at or above the target service temperature oroperating temperature of the device (e.g., a temperature of at leastabout 500° C., 550° C., 600° C., 650° C., 700° C., 800° C. or 900° C.).The secondary metallization metals may include, for example, Ti, Al, Cr,Mo, Ta, Nb and/or Ni. The resulting metallization metal alloy maycomprise Nb with greater than or equal to about 20 atomic-% (at %) Ti, 5at % Mo, 2 at % Mo, 5 at % Al, 5 at % Ni, 10 at % Si and/or 5 at % Cr.In some examples, the metallization metal alloy comprises greater thanor equal to about 50 at % Nb, 60 at % Nb, 70 at % Nb, 80 at % Nb, 90 at% Nb, or 95 at % Nb. In some examples, the metallization metal alloycomprises about 95 at % Nb and 5 at % Mo, 20 at % Ti and 80% Nb, 40 at %Ti and 60 at % Nb, 90 at % Nb and 5 at % each of Mo and Ni, or 80 at %Nb and 20 at % Al. In an example, Nb may have a CTE that closely matchesNd₂O₃ and a low Young's modulus (high elasticity), and may be made airstable by alloying with, for example, Ti, Mo, Al or Cr.

The metallization powder may comprise one or more ceramic or glassconstituents. A ceramic or glass constituent may react with the ceramicmaterial of the seal (also “seal ceramic material” herein) to form oneor more (e.g., new) ceramic or glass materials (e.g., compounds such as,for example, mutual reaction compounds of the ceramic material and theceramic or glass constituent of the metallization powder) that may, forexample, aid in creating a mechanical bond between the pre-metallizationlayer and the ceramic material. In an example, the seal ceramic materialcomprises AlN and the metallization powder comprises at least about 10%Mn, at least about 10%, 20%, 50%, or 70% Mo and at least about 2%, 5%,10% 15% or 20% Nd₂O₃. After the pre-metallization, the seal may comprisea layered structure including the bulk AlN seal ceramic material, alayer comprising Nd₂AlO₃N ceramic (e.g., formed as AlN+Nd₂O₃→Nd₂AlO₃Nduring melting and/or bonding of the seal ceramic material and themetallization powder) and a layer comprising Mn and/or Mo. In anotherexample, the seal ceramic material comprises Nd₂O₃ and the metallizationpowder comprises at least about 10% Mn, at least about 10% Mo and atleast about 2% AlN. After the pre-metallization, the seal may comprise alayered structure including the bulk Nd₂O₃ seal ceramic material, alayer comprising Nd₂AlO₃N ceramic (e.g., formed as Nd₂O₃+AlN→Nd₂AlO₃Nduring melting and/or bonding of the seal ceramic material and themetallization powder) and a layer comprising Mn and/or Mo. The bulk sealceramic material, the layer comprising Nd₂AlO₃N ceramic (e.g., an activelayer) and the layer comprising Mn and/or Mo (e.g., a protective layer)may form a pre-metallized ceramic component. At least one of themetallization layers (e.g., the active layer) may comprise one or morereaction products of the seal ceramic material and the metallizationpowder. In some cases, the metallization powder may comprise Nb metaland/or a Nb metal alloy mixed with a ceramic powder (e.g., Nd₂O₃, AlN,Y₂O₃, SrO, MgO, Al₂O₃ or TiO₂). For example, the metallization layer maycomprise a Nd alloy (e.g., about 95 at % Nb and about 5 at % Mo, about90% Nb and about 5 at % each of Mo and Ni, or about 80 at % Nb and about20 at % Ti) with at least about 5 mol %, 10 mol % or 15 mol % Nd₂O₃ceramic powder. In some cases, a size of the metallization powderparticles or a resulting metal or ceramic grain size may be less thanabout 1 micrometer (μm), 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm,60 μm, 80 μm, 100 μm, 150 μm or 500 μm. In some cases, open porosity ofthe metallization layer may be less than about 50%, 30%, 20%, 10%, 5%,2%, 1% or 0.5%.

The seal may further comprise one or more additional layers (e.g.,coated or plated onto the pre-metallized ceramic component or on eachother). For example, the seal may further comprise one or more platedand/or brazed layers of Ni, Ni alloy and/or Cu. The pre-metallized layer(e.g., a pre-metallized layer comprising Nd₂AlO₃N and Mn and/or Mosublayers, or a pre-metallized layer comprising W) may be Ni-plated(e.g., plated with Ni to prevent one or more portions of thepre-metallized layer such as, for example, tungsten, from oxidizing).This Ni-plated layer may be relatively thin. For example, the sealceramic material may be metallized with Mo/Mn and the metallizationlayer may then be Ni-plated, or the seal ceramic material may bemetallized with W and the metallization layer may then be Ni-plated. TheNi-plated layer (the Ni-plated pre-metallized ceramic component) maythen be brazed to a metal (e.g., Fe—Ni alloy, Ni or SS) collar or sleeveusing a braze comprising Cu or Ni (e.g., Cu, Ni or Ni alloy braze, suchas for example, a Cu braze foil, a Cu paste, a BNi-2, BNi-5b or BNi-9braze foil or a BNi-based braze paste). This braze layer may be thickerthan the Ni-plated layer. When using a Cu braze, the brazed assembly maybe Ni-plated after the brazing process (e.g., to cover the exposed Cuand/or to prevent the Cu from oxidizing or electromigrating). Forexample, after brazing with a Cu braze foil or paste, the braze jointmay have some Cu exposed (e.g., on the edge of the braze and metalcollar/sleeve joint). Such exposed metal surfaces may be Ni-plated(e.g., to ensure that the Cu is adequately covered to preventCu-electromigration).

The ceramic-to-metal seal joint may comprise metallization materialcomprising Mn and/or Mo that is bonded to the seal ceramic material. Themetallization material may also comprise one or more ceramic or glassconstituents. The metallization material may be bonded to the sealceramic material using, for example, a high temperature process. Forexample, the ceramic-to-metal seal joint may comprise Nd₂O₃ as the sealceramic material, a first metallization layer (e.g., an active layer)comprising Nd₂AlO₃N, a second metallization layer (e.g., a protectivelayer) comprising Mn, Mo, Nb, Ta and/or W, a first layer comprising Ni(e.g., a thin layer of Ni that is plated), a second layer comprising Ni(e.g., Ni alloy) or Cu (e.g., a braze layer of Ni, Ni alloy or Cu thatmay be thicker than the first layer), and a metal collar or sleeve(e.g., comprising greater than or equal to about 95% or 99% Ni, a Ni—Fealloy, 18CrCb ferritic stainless steel, 441 stainless steel, Inconel600, ATI alloy 600, Hastelloy S, or another stainless steel grade). Insome cases, when the second layer comprises Cu, at least a portion ofthe second layer (e.g., the portion that is not covered by the metalcollar or sleeve or by the first layer) may be covered by a third layercomprising Ni (e.g., another thin layer of Ni that is plated). In somecases, the second layer may comprise greater than or equal to about 82%Ni (e.g., BNi-2, BNi-9 braze or BNi-5b braze).

The ceramic-to-metal seal joint may comprise metallization materialcomprising W that is bonded to the seal ceramic material. Themetallization material may or may not also comprise one or more ceramicor glass constituents (e.g., the tungsten may in some cases be bondedwithout an oxide bonding layer, without a glass frit and/or withoutbeing mixed with a ceramic). The metallization material may be bonded tothe seal ceramic material using, for example, a high temperatureprocess. For example, the ceramic-to-metal seal joint may comprise AlNor Nd₂O₃ as the seal ceramic material, a metallization layer (e.g., anactive/protective layer) comprising W, a first layer comprising Ni(e.g., a thin layer of Ni that is plated), a second layer comprising Ni(e.g., Ni alloy) or Cu (e.g., a braze layer of Ni, Ni alloy or Cu thatmay be thicker than the first layer), and a metal collar or sleeve(e.g., comprising greater than or equal to about 95% or 99% Ni, a Ni—Fealloy, or a stainless steel). In some cases, when the second layercomprises Cu, at least a portion of the second layer (e.g., the portionthat is not covered by the metal collar or sleeve or by the first layer)may be covered by a third layer comprising Ni (e.g., another thin layerof Ni that is plated). In some cases, the second layer may comprisegreater than or equal to about 82% Ni (e.g., BNi-2, BNi9 or BNi-5bbraze).

In some implementations, a ceramic-to-metal brazed joint may be formedby a metallization process followed by a brazing process. In someimplementations, the metallization step may not be needed and theceramic-to-metal brazed joint may be formed directly by an active brazestep (e.g., using a Ti-containing braze).

The ceramic-to-metal seal joint may comprise a Nd₂O₃ ceramic material, ametallization layer, a braze layer, and a metal sleeve or collar. Theceramic material, metallization layer, braze layer, and metal sleeve orcollar may be sequentially bonded to each other to form a gas-tightbonded barrier/interface. For example, the ceramic-to-metal joint mayinclude a ceramic material comprising Nd₂O₃ which is bonded to ametallization layer comprising niobium (e.g., Nb—Ti, Nb—Mo, Nb—Ni orNb—Mo—Ni) and which may also be interspersed with ceramic particles(e.g., Nd₂O₃, AlN, Y₂O₃, TiO₂ and/or CaO), a braze layer (e.g., aNi-based braze alloy, such as, for example, BNi-2, BNi-9 or BNi-5bbraze), and a metal sleeve or collar (e.g., Fe- or Ni-based metal alloy,18CrCb ferritic stainless steel, 441 stainless steel, Inconel 600, ATIalloy 600, Hastelloy S or alloy 52). In an example, the ceramic-to-metaljoint may include a ceramic comprising Nd₂O₃ (e.g., Nd₂O₃ with greaterthan or equal to about 5 wt % SiC, 5 wt % ZrO₂ and/or 3 wt % Y₂O₃, orAlN with greater than or equal to about 3% Nd₂O₃), a Nd—Mo—Nimetallization layer (e.g., comprising about 85% Nb, 10% Mo and 5% Ni)interspersed with about 10 wt % Nd₂O₃ ceramic powder (e.g., with grainsize less than about 100 microns), a braze alloy layer of BNi-2, BNi-9or BNi-5b braze alloy, and a metal sleeve or collar (e.g., 18CrCbferritic stainless steel, 441 stainless steel, ATI alloy 600, HastelloyS or Inconel 600). The ceramic material layer may have a thickness ofgreater than about 1 mm, the metallization layer may have a thickness ofless than or equal to about 50 μm, the braze alloy layer may have athickness of less than or equal to about 100 μm, and the metal sleeve orcollar may have a thickness of greater than or equal to about 100 μm.

The ceramic-to-metal seal joint may comprise Nd₂O₃ ceramic material, atitanium-containing braze alloy (e.g., Ni alloys comprising Ti, Aland/or Si, such as, for example, Ni with about 27 wt % Ti and about 10wt % Al), and a metal sleeve or collar material (e.g., alloy 52, 18CrCbferritic stainless steel, 441 stainless steel, Inconel 600, ATI alloy600 or Hastelloy S). In an example, the ceramic-to-metal joint mayinclude an Nd₂O₃ ceramic material (e.g., Nd₂O₃ with greater than orequal to about 5 wt % SiC, 5 wt % ZrO₂ and/or 3 wt % Y₂O₃), a Ni—Ti—Albraze alloy layer, and a metal sleeve or collar of 18CrCb ferriticstainless steel. The ceramic material layer may have a thickness ofgreater than about 1 mm thickness, the metallization layer may have athickness of less than or equal to about 25 μm, the braze alloy layermay have a thickness of less than or equal to about 100 μm, and themetal sleeve or collar may have a thickness of greater than or equal toabout 75 μm.

Other suitable brazing material(s) may be added to the braze to improvechemical stability, change the melting temperature, or change mechanicalproperties (e.g., change the CTE of the braze, change the ductility ofthe braze, etc.). One or more layers may be formed under modifiedconditions (e.g., in a surrounding atmosphere with a differentcomposition or in the presence of a suitable reactive material). Suchmodifications may alter the composition of the aforementioned layeredstructure. The metal collar or sleeve may in some cases be substitutedby a different metal component (e.g., cell lid or body comprisingstainless steel) and/or combined with an additional metal component. Anyaspects of the disclosure described in relation to ceramic-to-metaljoints comprising a metal collar or sleeve may equally apply toceramic-to-metal joints comprising a metal component other than themetal collar or sleeve (e.g., a cell lid or body) at least in someconfigurations.

The ceramic material may comprise a main (also “primary” herein) ceramicmaterial (e.g., AlN, Nd₂O₃ or Y₂O₃) and a secondary ceramic materialthat is also thermodynamically stable, such as, for example, Y₂O₃, La₂O₃and/or any other ceramic material described herein (e.g., AlN, Be₃N₂,BN, Ca₃N₂, Si₃N₄, Al₂O₃, BeO, CaO, Ce₂O₃, Er₂O₃, MgO, Nd₂O₃, Sm₂O₃,Sc₂O₃, Yb₂O₃, ZrO₂, YPSZ, B₄C, SiC, TiC, ZrC, TiB₂, chalcogenides,quartz, glass, or any combination thereof). The main ceramic material(e.g., AlN or Nd₂O₃) may comprise, for example, greater than or equal toabout 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%,25%, 30%, 35%, 40%, or 45% of the secondary ceramic material (or acombination of secondary materials) by weight (or, in some cases, bymole or by volume). In some instances, the secondary ceramic materialserves to improve one or more characteristics of the ceramic (e.g.,increase the strength of the ceramic) by, for example, lowering asintering temperature of the ceramic (e.g., thereby reducing the grainsize), by forming a glassy phase between the grains of the main ceramicmaterial to promote tortuous crack growth path, and/or by one or moreother strengthening mechanisms for ceramic toughening. One or more ofsuch strengthening mechanisms may increase the energy required for acrack to propagate. In some cases, the primary and/or secondary ceramicmaterials may have different dimensions, geometries, aspect ratiosand/or other characteristics (e.g., regardless of the particle sizes).For example, a secondary ceramic material may be in a form thatincreases the strength of the ceramic, such as cuboidal-like shapes,spherical particles, elongated needle-like structures, whiskers, rodsand/or other suitable form(s). Elongated shapes, such as, for example,needle-like structures, whiskers and/or rods, may have an aspect ratio(e.g., the ratio between the smallest dimensional length and the longestdimensional length) of at least about 10, 20, 50, 100, 200, 500 or 1000.The secondary ceramic material (e.g., Y₂O₃ and/or SiC added to AlN) mayincrease the strength of the primary ceramic material by at least about0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%,40%, 50%, 60%, 70%, 80%, 90%, 100%, 120%, 140%, 160%, 180%, 200%, 250%,300%, 350%, 400%, 450%, 500%, 600%, 700%, 800%, 900%, 1000%, and thelike. A ceramic material comprising two or more ceramic materialcomponents (e.g., a primary ceramic material and a secondary ceramicmaterial) may substitute a ceramic material comprising a single ceramicmaterial component at least in some configurations, and vice versa.

The ceramic material may be densified (e.g., a material comprisingseparable powder particles may be converted to a more mechanicallyrobust material where the particles have fused together) through hightemperature processes such as, for example, sintering. In some cases,densification (e.g., sintering) may be performed to reduce an amount ofporosity (e.g., percentage of volume within the bulk of a ceramicmaterial not occupied by the ceramic material) from greater than orequal to about 50% (in an un-sintered sample) to less than or equal toabout 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1.5%, 1%, 0.75%, 0.5%, 0.25%or 0.1%. In some cases, the densified ceramic material may have adensity that is greater than or equal to about85%-of-theoretical-density (% TD), 90% TD, 92% TD, 94% TD, 96% TD, 98%TD or 99% TD (e.g., greater than about 96% TD). In some instances (e.g.,at levels greater than about 96% TD for some materials), pores may nolonger be connected to one another, the material may be substantiallygas-tight and/or rates of corrosion may be considerably reduced (e.g.,the density may reach “close pore” density). The sintering temperatureand/or sintering time may differ depending on sintering conditions(e.g., under different atmospheres). The sintering temperature may berelated to the sintering time (e.g., a lower sintering temperature mayrequire a longer sintering time). The sintering temperature of theceramic may be at least about 1000° C., 1200° C., 1300° C., 1400° C.,1500° C., 1600° C., 1700° C., 1800° C., 1900° C. or 2000° C. underdifferent atmospheres (e.g., air, nitrogen or argon). The sintering timeof the ceramic (e.g., at such temperatures and/or under differentatmospheres) may be at least about 10 minutes (min), 20 min, 30 min, 40min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min,180 min, 240 min or 300 min. For example, the ceramic may be sintered ata sintering temperature of at least about 1000° C., 1200° C., 1300° C.,1400° C., 1500° C., 1600° C., 1700° C., 1800° C., 1900° C. or 2000° C.under different atmospheres (e.g., air, nitrogen or argon) for a periodof at least about 10 minutes (min), 20 min, 30 min, 40 min, 50 min, 60min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 180 min, 240 minor 300 min. Sintering may be performed at a pressure of at less than orequal to about 0.1 atm, 0.5 atmospheres (atm), 0.95 atm, 1 atm, 2 atm, 5atm, 10 atm, 25 atm, 50 atm, 75 atm, 100 atm, 200 atm, 500 atm, 1000atm, 2000 atm, 5000 atm, 10,000 atm, 20,000 atm, 50,000 atm or 100,000atm (e.g., at such temperatures and/or under different atmospheres).

Sintering may be combined (or in some cases replaced) with one or moreother processing steps. Such processing steps may be applied before,during and/or after sintering. The processing may include, for example,one or more manufacturing processes used to reduce the porosity and/orincrease the density of a material. Manufacturing processes applied toone type of material (e.g., metal) may in some cases be advantageouslyapplied to another type of material (e.g., ceramic). In some cases, thesintering process may involve a “hot press” procedure where the ceramicpowder is heated to an elevated temperature in a controlled atmosphere(e.g., deep vacuum, partial vacuum, or a gas comprising Ar, N₂ and/orH₂) while a uniaxial force is applied to the ceramic to, for example,increase the rate of sintering, decrease the time it takes to reach agiven density (e.g., near or about 100% density), and/or decrease thesintering temperature. The uniaxial force may be, for example, at leastabout 0.01 MPa, 0.1 MPa, 1 MPa, 10 MPa, 20 MPa, 30 MPa, 50 MPa, 100 MPa,500 MPa or 1000 MPa. In some cases, a hot isostatic press (also known asa “HIP” processing) may be applied to the ceramic (e.g., aftersintering). The hot isostatic press may be applied to the ceramicdirectly after sintering. The hot isostatic press may be applied to theceramic at a temperature of less than or equal to about 1000° C., 1200°C., 1300° C., 1400° C., 1500° C., 1600° C., 1700° C., 1800° C., 1900° C.or 2000° C. The hot isostatic press may be applied to the ceramic (e.g.,at such temperatures) at a pressure of at least about 10 atm, 50 atm,100 atm, 200 atm, 500 atm, 1000 atm, 2000 atm, 5000 atm, 10,000 atm,20,000 atm, 50,000 atm or 100,000 atm. The hot isostatic press may beapplied to the ceramic (e.g., at such temperatures and/or pressures) fora period of at least about 10 min, 20 min, 30 min, 40 min, 50 min, 60min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 180 min, 240 minor 300 min. For example, the hot isostatic press may be applied to theceramic by changing the temperature to less than or equal to about 1000°C., 1200° C., 1300° C., 1400° C., 1500° C., 1600° C., 1700° C., 1800°C., 1900° C. or 2000° C. and increasing the pressure to at least about10 atm, 50 atm, 100 atm, 200 atm, 500 atm, 1000 atm, 2000 atm, 5000 atm,10,000 atm, 20,000 atm, 50,000 atm or 100,000 atm for a period of atleast about 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80min, 90 min, 100 min, 110 min, 120 min, 180 min, 240 min or 300 min.

The ceramic material may have a porosity (e.g., after densification bysintering) of less than or equal to about 5%, 4.5%, 4%, 3.5%, 3%, 2.5%,2%, 1.9%, 1.8%, 1.7%, 1.6%, 1.5%, 1.4%, 1.3%, 1.2%, 1.1%, 1%, 0.9%,0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.009%, 0.008%, 0.007%,0.006% or 0.005% (e.g., less than about 1% or 0.5%).

In some instances, the ceramic comprises a main ceramic material (e.g.,greater than about 50, 60, 70, 80, 90, 95 or more weight-%) that isthermodynamically stable with the contents of the cell (e.g., thereactive metal and molten salt), and a secondary ceramic material (e.g.,MgO) that is not stable (e.g., not stable with the contents of the cell,and/or not stable with the atmosphere outside the cell) at sufficientlylow quantities (e.g., less than about 40%, 35%, 30%, 25%, 20%, 15%, 10%or 5% on a weight, atomic, molar or volumetric basis). The secondaryceramic material may be present (e.g., exist) as particles dispersedthroughout the bulk of the main ceramic material (e.g., in such a waythat most of the secondary ceramic particles are not in direct contactwith other secondary ceramic particles). In some cases, the secondaryceramic material particles may strengthen the overall ceramic materialby establishing local regions of stress concentration to promote cracktip deflection and/or crack tip pinning. In some cases, the secondaryceramic material may be added to the main ceramic material to tune theCTE of the overall ceramic material to more closely match the CTE of themetal collar or sleeve and/or cell lid or body. In some cases, thesecondary ceramic material may be added to the main ceramic material toincrease overall strength. For example, the secondary ceramic materialmay be added to the main ceramic material to increase overall strengthby existing in a phase-transformation-able state that absorbs energy ascracks propagate through the ceramic (e.g., yttria-stabilized ZrO₂ withabout 3 mol % Y₂O₃). When exposed to reactive metal(s) and/or moltensalt(s) and/or air, the secondary ceramic particle on the surface may beattacked, but the secondary ceramic particles dispersed throughout thebulk of the main ceramic material may not be attacked, thus enabling theceramic material to be chemically stable when exposed to the reactivemetal(s) and/or molten salt(s).

The ceramic material (also “ceramic” herein) may comprise a primary(also “main” herein) ceramic material and one or more secondary ceramicmaterials. In some examples, the ceramic material comprises a primaryceramic material (e.g., yttrium oxide (Y₂O₃), neodymium oxide (Nd₂O₃) oraluminum nitride (AlN)) and greater than or equal to about 0.1%, 0.5%,1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 12.5%, 15%, 20%, 25%, 30%,35%, 40% or 45% by weight (also “weight percent,” “wt %” or “weight-%”herein) of a secondary ceramic material (e.g., aluminum nitride (AlN),beryllium nitride (Be₃N₂), boron nitride (BN), calcium nitride (Ca₃N₂),silicon nitride (Si₃N₄), aluminum oxide (Al₂O₃, also “alumina” herein),beryllium oxide (BeO), calcium oxide (CaO), cerium oxide (Ce₂O₃), erbiumoxide (Er₂O₃), lanthanum oxide (La₂O₃), magnesium oxide (MgO, also“magnesia” herein), yttrium oxide (Y₂O₃, also “yttria” herein),neodymium oxide (Nd₂O₃, also “neodymia” herein), samarium oxide (Sm₂O₃),scandium oxide (Sc₂O₃), yttrium oxide (Yb₂O₃, also “yttria” herein),zirconium oxide (ZrO₂, also “zirconia” herein), yttria partiallystabilized zirconia (YPSZ), tetragonal zirconia polycrystal (TZP), e.g.,tetragonal crystal structure ZrO₂ with about 3 mol % Y₂O₃), boroncarbide (B₄C), silicon carbide (SiC), titanium carbide (TiC), zirconiumcarbide (ZrC), titanium diboride (TiB₂), chalcogenides, quartz, glass,or any combination thereof). In some examples, the ceramic materialcomprises a primary ceramic material and less than about 0.1%, 0.5%, 1%,2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 12.5%, 15%, 20%, 25%, 30%,35%, 40% or 45% by weight of a secondary ceramic material. A givenceramic material (e.g., Y₂O₃, Nd₂O₃ or AlN) may be a primary ceramicmaterial in some instances and a secondary ceramic material in otherinstances. In some examples, the ceramic comprises a primary ceramicmaterial (e.g., Y₂O₃, Nd₂O₃ or AlN) with greater than or equal to about0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 12.5%, 15%,20%, 25%, 30%, 35%, 40% or 45% by weight of a secondary ceramic material(or a combination of secondary ceramic materials). In some examples, theceramic comprises a primary ceramic material (e.g., Y₂O₃, Nd₂O₃ or AlN)with less than about 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%,10%, 12%, 12.5%, 15%, 20%, 25%, 30%, 35%, 40% or 45% by weight of asecondary ceramic material (or a combination of secondary ceramicmaterials). The ceramic material may be substantially or wholly formedof the primary ceramic material. The amount/level/concentration of thesecondary ceramic material may apply to an individual secondary ceramicmaterial (e.g., the amount of the secondary ceramic material may applyto each individual secondary ceramic material, the ceramic material maycomprise individual secondary ceramic materials in the same or differentamounts, etc.) in a mixture of secondary ceramic materials, or to thesecondary ceramic material mixture as a whole. Such compositions may beprovided, for example, using primary and/or secondary ceramicmaterial(s) that comprise grains (e.g., grains of given grain size(s)).

Other additives may also be included in the ceramic material and/or thesecondary ceramic material(s) at lower amounts/levels (e.g., as othersmaller percentage additives). Such amount/levels may be, for example,less than or equal to about 3%, 2.5%, 2%, 1.8%, 1.6%, 1.4%, 1.2%, 1%,0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, 0.025%,0.01% or 0.005% (e.g., wt % or mol %) of the ceramic material, or of oneor more secondary ceramic materials. In an example, SiC secondaryceramic material may contain less than or equal to about 2% carbon andless than or equal to about 0.5% boron. In another example, TZP maycomprise less than or equal to about 3 mol % Y₂O₃ and/or less than orequal to about 0.1-0.4 wt % Al₂O₃.

The ceramic material may comprise Nd₂O₃. The ceramic material maycomprise a primary ceramic material (e.g., Nd₂O₃), and one or moresecondary ceramic materials (e.g., Y₂O₃, SiC, AlN, TiC, ZrO₂, TZP, orany combination thereof). The ceramic material may be substantially orwholly formed of the primary ceramic material. The ceramic material maycomprise various levels of secondary ceramic material(s). For example,the ceramic material may comprise a first secondary ceramic material anda second secondary ceramic material. The ceramic material may comprisethe first secondary ceramic material (e.g., Y₂O₃) at a concentrationgreater than or equal to about 3 wt %, 5 wt % or 10 wt %. As analternative, the ceramic material may comprise the first secondaryceramic material (e.g., Y₂O₃) at a concentration less than about 10 wt%, 5 wt % or 3 wt %. The ceramic material may comprise the firstsecondary ceramic material in combination with at least the secondsecondary ceramic material (e.g., SiC, AlN, TiC, ZrO₂ or TZP), thesecond secondary ceramic material being at a concentration greater thanor equal to about 3 wt % or 5 wt %. As an alternative, the ceramicmaterial may comprise the first secondary ceramic material incombination with at least the second secondary ceramic material (e.g.,SiC, AlN, TiC, ZrO₂ or TZP), the second secondary ceramic material beingat a concentration less than about 5 wt % or 3 wt %. The ceramicmaterial may comprise the second secondary ceramic material without thefirst secondary ceramic material. The first secondary material may beselected, for example, among the aforementioned one or more secondarymaterials (e.g., SiC, AlN, TiC, ZrO₂ or TZP may be selected instead ofY₂O₃). The second secondary material may then be suitably selected fromthe remainder of the one or more secondary ceramic materials. Theceramic material may comprise additional secondary ceramic materials(e.g., at similar or different concentrations). Such additionalsecondary ceramic materials may be selected, for example, among theaforementioned one or more secondary ceramic materials not selected asthe first secondary ceramic material and the second secondary ceramicmaterial. The ceramic material and/or the secondary ceramic material(s)may comprise one or more additives as described elsewhere herein.

The ceramic material may have a tensile yield strength greater than orequal to about 50 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa, 600 MPa, 700 MPa, 800 MPa, 900MPa or 1000 MPa.

There are various examples of such ceramic material compositions. Theceramic material may comprise Nd₂O₃ (e.g., greater than about 30 wt %Nd₂O₃), and greater than or equal to about 3 wt % SiC. The ceramicmaterial may comprise Nd₂O₃ (e.g., greater than 30 wt % Nd₂O₃), andgreater than or equal to about 3 wt % Y₂O₃ and/or greater than or equalto about 3 wt % SiC. The ceramic material may comprise Nd₂O₃ (e.g.,greater than about 30 wt % Nd₂O₃), and greater than or equal to about 3wt % Y₂O₃ and/or greater than or equal to about 5% SiC. The ceramicmaterial may comprise Nd₂O₃ (e.g., greater than about 30 wt % Nd₂O₃),and less than or equal to about 3 wt % Y₂O₃ and/or greater than or equalto about 5% SiC. The ceramic material may comprise Nd₂O₃ (e.g., greaterthan about 30 wt % Nd₂O₃), and less than or equal to about 5 wt % SiC.The ceramic material may comprise Nd₂O₃, and less than or equal to about5 wt % Y₂O₃ and/or less than or equal to about 5 wt % SiC. The ceramicmaterial may comprise Nd₂O₃, and less than or equal to about 5 wt % Y₂O₃and/or greater than or equal to about 5 wt % SiC. The ceramic materialmay comprise Nd₂O₃, and less than or equal to about 10 wt % Y₂O₃ and/orgreater than or equal to about 5 wt % SiC. The ceramic material maycomprise Nd₂O₃, and less than or equal to about 10 wt % Y₂O₃ and/or lessthan about 5 wt % SiC. In an example, the ceramic material comprisesNd₂O₃, and less than about 5 wt % Y₂O₃ and greater than about 5 wt %SiC. The ceramic material may comprise Nd₂O₃ (e.g., greater than about30 wt % Nd₂O₃), and greater than or equal to about equal to 5 wt % TiC.The ceramic material may comprise Nd₂O₃ (e.g., greater than about 30 wt% Nd₂O₃), and greater than or equal to about 5 wt % TiC and greater thanor equal to about 3 wt % ZrO₂.

The composition of a material (e.g., ceramic material) may be described,defined and/or specified in various ways. The composition of a ceramicmaterial may be specified in terms of the composition of the rawmaterials (e.g., powders) used to create the ceramic material. Forexample, if a ceramic material is fabricated from and/or comprises about90 wt % Nd₂O₃ powder, 5 wt % TZP powder and 5 wt % SiC powder, theceramic material composition may be specified in terms of itsconstituents as about 90 wt % Nd₂O₃, 5 wt % TZP and 5 wt % SiC. Duringthe sintering process (e.g., hot pressing or HIP), the constituents maychange phase and/or interact with each other. For example, TZP mayinteract with Nd₂O₃ in one or more ways, including, for example, formingNd₂Zr₂O₇ as a separate phase from both TZP and Nd₂O₃, and/or diffusinginto the Nd₂O₃ crystal structure. During diffusion into the Nd₂O₃crystal structure, the Zr atoms may substitutionally replace Nd atoms inthe crystal structure to create a mixed composition with a crystalstructure similar to the Nd₂O₃ crystal structure (e.g., (Nd,Zr)₂O₃). Insome cases, more than two metal elements may exist in the same crystalstructure (e.g., Y₂O₃ and ZrO₂ may both diffuse into the Nd₂O₃ crystalstructure to make (Nd,Zr,Y)₂O₃). In an example, the ceramic material maycomprise greater than about 30 wt % Nd₂O₃, and less than or equal toabout 5 wt % Y₂O₃, at greater than or equal to about 15 wt % Nd₂Zr₂O₇,and greater than or equal to about 5 wt % SiC. Such a composition ofcrystal structures/phases (or at least a subset thereof) may result fromsintering and/or may be used in as a raw material.

As evidenced, for example, by the presence and amounts of the remainingold phase (e.g., TZP), new phase (e.g., Nd₂Zr₂O₇) and changedneighboring phase(s) (e.g., (Nd,Zr)₂O₃), the composition of a sinteredceramic material may be specified in multiple ways in addition to (orbased on) the composition of the raw materials (e.g., powders) used tomake a ceramic material.

In one approach, the composition of a ceramic material may be specifiedin terms of the atomic percent (also “atomic-%” and “at %” herein) of anelement in the ceramic material (e.g., in the final (e.g., sintered)ceramic material). For example, the atomic percentage of Nd, Y, Zr, O,Si and/or C atoms in a ceramic material may be measured and used as away to specify the composition of the ceramic material. Methods formeasuring atomic percentages in a material may include, for example,mass spectroscopy (e.g., inductively coupled plasma mass spectroscopy(ICP-MS)) and/or other established analytical techniques. Sometechniques, such as ICP-MS, may include dissolving a material in asolution (e.g., aqueous and/or acidic bath containing H₂O), thus makingit difficult to determine the relative atomic percent of certainelements (e.g., H, O). The composition of the ceramic material maytherefore be specified by measuring the “relative” atomic percentages ofa group of elements (e.g., metals, or a list of elements excluding O, H,C, and/or N). In an example, a ceramic material is specified in terms ofthe atomic percentages of metallic elements or a subset of all theelements (e.g., elements excluding H, C, O, N). Other techniques (e.g.,combustion and infrared detection, inert gas fusion, vacuum hotextraction, etc.) may be used to detect remaining atoms (e.g., H, C, O,N) present in the ceramic material. In some instances, multipledifferent analytical techniques can be used on different portions of thesame material to determine atoms present and establish an accurateatomic percentage composition measurement of all elements present.

Another approach to specifying the composition of a ceramic material mayinclude specifying the crystal structures present as measured throughsome analytical technique (e.g., X-ray diffraction (XRD)). Crystalstructure analysis may provide estimates of the composition of thematerial, but may not reach desired levels of precision of each measuredphase. For example, a ceramic material fabricated from 85 wt % Nd₂O₃, 5wt % Y₂O₃, 5 wt % TZP and 5 wt % SiC may be analyzed using crystalstructure analysis (e.g., XRD). The analysis may detect the presence ofNd₂O₃, Nd₂Zr₂O₇, (Nd,Zr)₂O₃, Y₂O₃, SiO₂, NdC₂ and/or SiC crystalstructures; however, this process may not be able to providesufficiently precise relative amounts (e.g., the analysis may be unableto resolve within less than about 2% or 10% of each crystal structurepresent in a sample). The composition of the ceramic material maytherefore be specified by specifying which crystal structures arepresent in the ceramic material (e.g., in the final ceramic material)and the relative atomic percentages (either based on all types ofelements in the sample, or based on a subset of elements, such as, forexample, the relative percentages of metals in the sample). For example,the composition of a material comprising 85 wt % Nd₂O₃, 5 wt % Y₂O₃, 5wt % TZP and 5 wt % SiC may be specified in terms of the relative wt %,vol % and/or mol % of raw materials, and/or may be specified as amaterial comprising Nd₂O₃, Y₂O₃, (Nd,Zr,Y)₂O₃, NdZr₂O₇ and/or SiCcrystal structures with about 71 at % Nd, 6 at % Y, 17 at % Si and 6 at% Zr on a metals basis (excluding O and C atoms) or about 29 at % Nd, 3at % Y, 7 at % Si, 7 at % C, 2 at % Zr and 52 at % O (accounting for allelements).

The relative atomic percentages of elements and/or metal may becalculated and/or determined based on the relative percentages of rawmaterials (compounds) in a given ceramic composition (e.g., in wt % ormol %). Compositions of ceramic materials specified herein in terms ofthe relative amounts of the raw materials (e.g., powders) used tofabricate the ceramic material may therefore also cover or includeceramic materials specified in terms of crystal structures present(e.g., in a final state) and/or atomic percentages (e.g., relativeatomic percentages based on all elements present or on a subset ofelements such as metals or elements excluding H, O and/or C). It will beappreciated that a ceramic composition specified herein in terms of araw material composition may include or be equivalent to one or moreceramic compositions with (i) atomic percentages (e.g., atomicpercentages as measured in the final ceramic material or in anyintermediate states) corresponding to the raw material composition(e.g., specification of raw material(s) also covers the final materialas specified in at %), (ii) one or more crystal structures (e.g., numberand/or identity of crystal structures) resulting (e.g., after sintering)from the raw materials, or (iii) a combination thereof (e.g., if rawmaterials are specified then the final material can be specified). Agiven raw material composition may result in one or more final materialshaving the same atomic percentages, and the same or different crystalstructure(s). For example, crystal structure(s) may depend on sinteringconditions. Ceramic materials specified herein in terms of raw materialcompositions and/or atomic percentages may be understood to includefinal materials having any crystal structure(s). Such crystalstructure(s) may be as described herein (e.g., in relation to TABLE 4).It will also be appreciated that a given final ceramic composition maybe obtained using different raw materials. For example, different rawpowders may be used to fabricate a ceramic material with the same finalcomposition in atomic percent. The composition in atomic percentages(e.g., as specified, or as calculated based on raw material composition)may therefore be understood to define a ceramic material compositionfabricated or manufactured from any raw material composition/mixture(e.g., from a raw material composition that includes Nd₂Zr₂O₇ as well asfrom (e.g., instead of) a raw material composition that includes Nd₂O₃and ZrO₂). The ceramic material may have such atomic percentages at anypoint in time (e.g., during and after sintering, or throughout any othertransformation). Further, it will be appreciated that a ceramiccomposition specified in terms of, for example, intermediate crystalstructures (e.g., crystal structures present at any point duringsintering and/or other transformation) may be the same ceramiccomposition as specified herein in terms of raw material composition,atomic percentages and/or final crystal structure(s). Any aspects of thedisclosure described in relation to a ceramic composition specified interms of raw material composition may equally apply to a ceramiccomposition specified in terms of atomic percent and/or in terms ofcrystal structure(s) or phase(s) present (e.g., in the final material,or in some cases, in one or more intermediate materials).

In some cases, individual ceramic compounds (e.g., Nd₂O₃, Y₂O₃, TZP orSiC) may exist as multiple different crystal structures (e.g., the samecompound, say, Nd₂O₃, may exist as a hexagonal phase, cubic or amonoclinic crystal structure/phase). In some cases, one or more given(e.g., specific) crystal structures may be desired as they may provideimproved chemical, electrical, mechanical or thermal properties (e.g.,improved corrosion resistance, chemical stability, electricalresistance, bond strength with metallization or braze layer, strength,fracture toughness and/or CTE). Further details may be provided tofurther specify or define a ceramic material, including, for example,nominal grain size of constituent materials/compounds (which may be thesame for each constituent material/compound, or different for differentconstituent material/compounds), typical shape or form of constituentmaterials/grains (e.g., spherical, whiskers or rods), porosity, and/orother physical properties as described elsewhere herein (e.g., CTE,yield strength, fracture toughness and/or chemical stability).

Some examples of ceramic material compositions comprising Nd₂O₃ areprovided in TABLE 4. Examples of raw materials with amounts/levels,atomic percentages (including oxygen and carbon atoms), and crystalstructures that may be present in the resulting (e.g., final) ceramicmaterials are provided. It will be appreciated that only a subset of thelisted phases may be present (e.g., see examples provided in parenthesesin the rightmost “Crystal structures” column in TABLE 4). The firstceramic material constituent in each row in the “Ceramic constituents”column may be considered the primary ceramic material (e.g., Nd₂O₃), andall other ceramic materials in the row may be considered secondaryceramic materials.

The ceramic material may comprise a given ceramic constituent at a levelgreater than or equal to one or more given values, at a level less thanor equal to one or more given values, or a combination thereof. Forexample, composition #1 may comprise less than or equal to about 98 wt %of the ceramic constituent Nd₂O₃, greater than or equal to about 30 wt %or 50 wt % of the ceramic constituent Nd₂O₃, or a combination thereof. Acombination of upper and lower bounds (limits) may define a range (e.g.,range with or without endpoint(s) included). The primary ceramicmaterial (e.g., Nd₂O₃) may form greater than or equal to about 30 wt %,40 wt %, 50 wt %, 60 wt % or 70 wt % of the ceramic material for thecompositions listed in TABLE 4 (e.g., the primary ceramic material mayform greater than about 30 wt %, 40 wt %, 50 wt %, 60 wt % or 70 wt % ofthe final ceramic material). For example, composition #1 may comprisebetween about 30 wt %, 40 wt %, 50 wt %, 60 wt % or 70 wt % and 98 wt %Nd₂O₃, composition #17 may comprise between about 30 wt % or 40 wt % and50 wt % Nd₂O₃, and composition #18 may comprise between about 30 wt %and 40 wt % Nd₂O₃. Examples of such ranges are provided in TABLE 4.

Also provided in TABLE 4 are examples of atomic percentages. Forexample, composition #1 may comprise less than or equal to about 38.8 at% Nd, greater than or equal to about 15 at % Nd, or a combinationthereof (between about 15 at % and 38.8 at % Nd).

TABLE 4 EXAMPLES OF CERAMIC MATERIAL COMPOSITIONS Ceramic constituentsAtomic percentages Crystal structures that may be present # (wt %)examples/ranges and examples 1 Nd₂O₃ (e.g., ≤~98 Nd: ≤~38.8%, ≥~15%Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~1.2%Nd₂O₃, Y₂O₃ and/or (Nd, Y)₂O₃ Y₂O₃ (e.g., ≥~2 wt %) O: ≤~60% (e,g.,monoclinic (Nd, Y)₂O₃) 2 Nd₂O₃ (e.g., ≤~98 Nd: ≤~38.7%, ≥~15%Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Zr:≥~1.1% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~2 wt %) O: ≤~60.2% Cubicor orthorhombic Nd₂Zr₂O₇ Tetragonal ZrO₂ (e,g., at least one ofmonoclinic Nd₂O₃ and cubic Nd₂Zr₂O₇; at least one of monoclinic Nd₂O₃,cubic Nd₂Zr₂O₇ and tetragonal ZrO₂) 3 Nd₂O₃ (e.g., ≤~98 Nd: ≤~38.2%,≥~15% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Ti:≥~2.2% Nd₂O₃ TiC (e.g., ≥~2 wt %) C: ≥~3.2% Cubic or hexagonal TiO₂ O:≤~57.4% (e,g., at least one of monoclinic Nd₂O₃ and cubic TiC) 4 Nd₂O₃(e.g., ≤~98 Nd: ≤~37.4%, ≥~15% Monoclinic, cubic and/or hexagonal wt %,≥~30 wt %, ≥~50 wt %) Si: ≥~3.2% Nd₂O₃ SiC (e.g., ≥~2 wt %) C: ≥~3.2%Cubic and/or hexagonal SiC O: ≤~56.2% (e,g., at least one of monoclinicNd₂O₃ and hexagonal SiC) 5 Nd₂O₃ (e.g., ≤~96 Nd: ≤~36.3%, ≥~15%Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~1.1%Nd₂O₃, Y₂O₃ and/or (Nd, Y)₂O₃ Y₂O₃ (e.g., ≥~2 wt %) Si: ≥~3.2% Cubicand/or hexagonal SiC SiC (e.g., ≥~2 wt %) C: ≥~3.2% (e,g., at least oneof monoclinic O: ≤~56.2% (Nd, Y)₂O₃ and hexagonal SiC) 6 Nd₂O₃ (e.g.,≤~90 Nd: ≤~31.5%, ≥~15% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt%, ≥~50 wt %) Y: ≥~2.6% Nd₂O₃, Y₂O₃ and/or (Nd, Y)₂O₃ Y₂O₃ (e.g., ≥~5 wt%) Si: ≥~7.3% Cubic and/or hexagonal SiC SiC (e.g., ≥~5 wt %) C: ≥~7.3%(e,g., at least one of monoclinic O: ≤~51.2% (Nd, Y)₂O₃ and hexagonalSiC) 7 Nd₂O₃ (e.g., ≤~94 Nd: ≤~36.4%, ≥~15% Monoclinic, cubic and/orhexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~1.7% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃,(Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~3 wt %) Zr: ≥~1.6% and/or (Nd, Y, Zr)₂O₃ ZrO₂(e.g., ≥~3 wt %) O: ≤~60.3% Cubic or orthorhombic Nd₂Zr₂O₇ Monoclinicand/or tetragonal ZrO₂ (e,g., at least one of monoclinic (Nd, Y)₂O₃, andtetragonal ZrO₂; at least one of monoclinic (Nd, Y)₂O₃, cubic Nd₂Zr₂O₇and tetragonal ZrO₂) 8 Nd₂O₃ (e.g., ≤~90 Nd: ≤~34.1%, ≥~15% Monoclinic,cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~2.8% Nd₂O₃,Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %) Zr: ≥~2.6% and/or(Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~5 wt %) O: ≤~60.5% Cubic or orthorhombicNd₂Zr₂O₇ Monoclinic and/or tetragonal ZrO₂ (e,g., at least one ofmonoclinic (Nd, Y)₂O₃ and tetragonal ZrO₂; at least one of monoclinic(Nd, Y)₂O₃, cubic Nd₂Zr₂O₇ and tetragonal ZrO₂) 9 Nd₂O₃ (e.g., ≤~85 Nd:≤~29%, ≥~15% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt%) Y: ≥~2.5% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %)Zr: ≥~2.3% and/or (Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~5 wt %) Si: ≥~7.1% Cubicand/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~5 wt %) C: ≥~7.1% and/orNd₂(Zr, Si)₂O₇ O: ≤~51.9% Monoclinic and/or tetragonal ZrCO₂ Cubicand/or hexagonal SiC (e,g., at least one of monoclinic (Nd, Y)₂O₃,tetragonal ZrO₂ and hexagonal SiC; at least one of monoclinic (Nd, Y,Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 10Nd₂O₃ (e.g., ≤~80 Nd: ≤~26.5%, ≥~10% Monoclinic, cubic and/or hexagonalwt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~2.5% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd,Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %) Zr: ≥~4.5% and/or (Nd, Y, Zr)₂O₃ ZrO₂(e.g., ≥~10 wt %) Si: ≥~7% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC (e.g.,≥~5 wt %) C: ≥~7% and/or Nd₂(Zr, Si)₂O₇ O: ≤~52.6% Monoclinic and/ortetragonal ZrO₂ Cubic and/or hexagonal SiC (e,g., at least one ofmonoclinic (Nd, Y)₂O₃, tetragonal ZrO₂ and hexagonal SiC; at least oneof monoclinic (Nd, Y, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ andhexagonal SiC) 11 Nd₂O₃ (e.g., ≤~80 Nd: ≤~24.8%, ≥~10% Monoclinic, cubicand/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~2.3% Nd₂O₃, Y₂O₃, (Nd,Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %) Zr: ≥~2.1% and/or (Nd, Y,Zr)₂O₃ ZrO₂ (e.g., ≥~5 wt %) Si: ≥~13% Cubic and/or orthorhombicNd₂Zr₂O₇ SiC (e.g., ≥~10 wt %) C: ≥~13% and/or Nd₂(Zr, Si)₂O₇ O: ≤~44.8%Monoclinic and/or tetragonal ZrO₂ Cubic and/or hexagonal SiC (e,g., atleast one of monoclinic (Nd, Y, Zr)₂O₃, tetragonal ZrO₂ and hexagonalSiC; at least one of monoclinic (Nd, Y, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇,tetragonal ZrO₂ and hexagonal SiC) 12 Nd₂O₃ (e.g., ≤~75 Nd: ≤~22.7%,≥~10% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y:≥~2.3% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %) Zr:≥~4.1% and/or (Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~10 wt %) Si: ≥~12.7% Cubicand/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~10 wt %) C: ≥~12.7% and/orNd₂(Zr, Si)₂O₇ O: ≤~45.6% Monoclinic and/or tetragonal ZrO₂ Cubic and/orhexagonal SiC (e,g., at least one of monoclinic (Nd, Y)₂O₃ tetragonalZrO₂ and hexagonal SiC; at least one of monoclinic (Nd, Y, Zr)₂O₃, cubicNd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 13 Nd₂O₃ (e.g., ≤~70Nd: ≤~20.7%, ≥~10% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %,≥~50 wt %) Y: ≥~2.2% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g.,≥~5 wt %) Zr: ≥~6.0% and/or (Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~15 wt %) Si:≥~12.4% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~10 wt %) C:≥~12.4% and/or Nd₂(Zr, Si)₂O₇ O: ≤~46.4% Monoclinic and/or tetragonalZrO₂ Cubic and/or hexagonal SiC (e,g., at least one of monoclinic (Nd,Y)₂O₃ tetragonal ZrO₂ and hexagonal SiC; at least one of monoclinic (Nd,Y, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 14Nd₂O₃ (e.g., ≤~70 Nd: ≤~19.4%, ≥~10% Monoclinic, cubic and/or hexagonalwt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~2.1% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd,Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %) Zr: ≥~3.8% and/or (Nd, Y, Zr)₂O₃ ZrO₂(e.g., ≥~10 wt %) Si: ≥~17.5% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC(e.g., ≥~15 wt %) C: ≥~17.5% and/or Nd₂(Zr, Si)₂O₇ O: ≤~39.8% Monoclinicand/or tetragonal ZrO₂ Cubic and/or hexagonal SiC (e,g., at least one ofmonoclinic (Nd, Y)₂O₃ tetragonal ZrO₂ and hexagonal SiC; at least one ofmonoclinic (Nd, Y, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ andhexagonal SiC) 15 Nd₂O₃ (e.g., ≤~65 Nd: ≤~17.6%, ≥~8% Monoclinic, cubicand/or hexagonal wt % ≥~30 wt %, ≥~50 wt %) Y: ≥~2.0% Nd₂O₃, Y₂O₃, (Nd,Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt %) Zr: ≥~5.6% and/or (Nd, Y,Zr)₂O₃ ZrO₂ (e.g., ≥~15 wt %) Si: ≥~17.1% Cubic and/or orthorhombicNd₂Zr₂O₇ SiC (e.g., ≥~15 wt %) C: ≥~17.1% and/or Nd₂(Zr, Si)₂O₇ O:≤~40.6% Monoclinic and/or tetragonal ZrO₂ Cubic and/or hexagonal SiC(e,g., at least one of monoclinic (Nd, Y)₂O₃ tetragonal ZrO₂ andhexagonal SiC; at least one of monoclinic (Nd, Y, Zr)₂O₃, cubic Nd₂(Zr,Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 16 Nd₂O₃ (e.g., ≤~65 Nd:≤~18.7%, ≥~8% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50wt %) Y: ≥~2.1% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt%) Zr: ≥~7.9% and/or (Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~20 wt %) Si: ≥~12.1%Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~10 wt %) C: ≥~12.1%and/or Nd₂(Zr, Si)₂O₇ O: ≤~47.1% Monoclinic and/or tetragonal ZrO₂ Cubicand/or hexagonal SiC (e,g., at least one of monoclinic (Nd, Y)₂O₃tetragonal ZrO₂ and hexagonal SiC; at least one of monoclinic (Nd, Y,Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 17Nd₂O₃ (e.g., ≤~50 Nd: ≤~12.1%, ≥~6% Monoclinic, cubic and/or hexagonalwt %, ≥~30 wt %) Y: ≥~3.6% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃(e.g., ≥~10 wt %) Zr: ≥~6.6% and/or (Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~20 wt%) Si: ≥~20.4% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~20 wt %)C: ≥~20.4% and/or Nd₂(Zr, Si)₂O₇ O: ≤~36.9% Monoclinic and/or tetragonalZrO₂ Cubic and/or hexagonal SiC (e,g., at least one of monoclinic (Nd,Y)₂O₃ tetragonal ZrO₂ and hexagonal SiC; at least one of monoclinic (Nd,Y, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 18Nd₂O₃ (e.g., ≤~40 Nd: ≤~8.9%, ≥~8% Monoclinic, cubic and/or hexagonal wt%, ≥~30 wt %) Y: ≥~3.3% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g.,≥~10 wt %) Zr: ≥~7.6% and/or (Nd, Y, Zr)₂O₃ ZrO₂ (e.g., ≥~25 wt %) Si:≥~23.3% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~25 wt %) C:≥~23.3% and/or Nd₂(Zr, Si)₂O₇ O: ≤~33.5% Monoclinic and/or tetragonalZrO₂ Cubic and/or hexagonal SiC (e,g., at least one of monoclinic (Nd,Y)₂O₃ tetragonal ZrO₂ and hexagonal SiC; at least one of monoclinic (Nd,Y, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 19Nd₂O₃ (e.g., ≤~94 Nd: ≤~36.2%, ≥~15% Monoclinic, cubic and/or hexagonalwt %, ≥~30 wt %, ≥~50 wt %) Zr: ≥~1.0% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂(e.g., ≥~2 wt %) Si: ≥~3.2% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC(e.g., ≥~2 wt %) C: ≥~3.2% and/or Nd₂(Zr, Si)₂O₇ O: ≤~56.4% Monoclinicand/or tetragonal ZrO₂ Cubic and/or hexagonal SiC (e,g., at least one ofmonoclinic Nd₂O₃, tetragonal ZrO₂ and hexagonal SiC; at least one ofmonoclinic (Nd, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ andhexagonal SiC) 20 Nd₂O₃ (e.g., ≤~90 Nd: ≤~31.3%, ≥~15% Monoclinic, cubicand/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Zr: ≥~2.4% Nd₂O₃ and/or(Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~5 wt %) Si: ≥~7.3% Cubic and/or orthorhombicNd₂Zr₂O₇ SiC (e.g., ≥~5 wt %) C: ≥~7.3% and/or Nd₂(Zr, Si)₂O₇ O: ≤~51.7%Monoclinic and/or tetragonal ZrO₂ Cubic and/or hexagonal SiC (e,g., atleast one of monoclinic Nd₂O₃, tetragonal ZrO₂ and hexagonal SiC; atleast one of monoclinic (Nd, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonalZrO₂ and hexagonal SiC) 21 Nd₂O₃ (e.g., ≤~80 Nd: ≤~24.6%, ≥~10%Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Zr:≥~4.2% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~10 wt %) Si: ≥~12.9% Cubicand/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~10 wt %) C: ≥~12.9% and/orNd₂(Zr, Si)₂O₇ O: ≤~45.3% Monoclinic and/or tetragonal ZrO₂ Cubic and/orhexagonal SiC (e,g., at least one of monoclinic Nd₂O₃, tetragonal ZrO₂and hexagonal SiC; at least one of monoclinic (Nd, Zr)₂O₃, cubic Nd₂(Zr,Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 22 Nd₂O₃ (e.g., ≤~75 Nd:≤~23.1%, ≥~10% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50wt %) Zr: ≥~2.0% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~5 wt %) Si:≥~18.2% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC (e.g., ≥~15 wt %) C:≥~18.2% and/or Nd₂(Zr, Si)₂O₇ O: ≤~38.6% Monoclinic and/or tetragonalZrO₂ Cubic and/or hexagonal SiC (e,g., at least one of monoclinic Nd₂O₃,tetragonal ZrO₂ and hexagonal SiC; at least one of monoclinic (Nd,Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ and hexagonal SiC) 23Nd₂O₃ (e.g., ≤~75 Nd: ≤~26.4%, ≥~10% Monoclinic, cubic and/or hexagonalwt %, ≥~30 wt %, ≥~50 wt %) Zr: ≥~6.8% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂(e.g., ≥~15 wt %) Si: ≥~6.9% Cubic and/or orthorhombic Nd₂Zr₂O₇ SiC(e.g., ≥~5 wt %) C: ≥~6.9% and/or Nd₂(Zr, Si)₂O₇ O: ≤~53.1% Monoclinicand/or tetragonal ZrO₂ Cubic and/or hexagonal SiC (e,g., at least one ofmonoclinic Nd₂O₃, tetragonal ZrO₂ and hexagonal SiC; at least one ofmonoclinic (Nd, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂ andhexagonal SiC) 24 Nd₂O₃ (e.g., ≤~70 Nd: ≤~19.3%, ≥~10% Monoclinic, cubicand/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Zr: ≥~5.7% Nd₂O₃ and/or(Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~15 wt %) Si: ≥~17.4% Cubic and/or orthorhombicNd₂Zr₂O₇ SiC (e.g., ≥~15 wt %) C: ≥~17.4% and/or Nd₂(Zr, Si)₂O₇ O:≤~40.3% Monoclinic and/or tetragonal ZrO₂ Cubic and/or hexagonal SiC(e,g., at least one of monoclinic Nd₂O₃, tetragonal ZrO₂ and hexagonalSiC; at least one of monoclinic (Nd, Zr)₂O₃, cubic Nd₂(Zr, Si)₂O₇,tetragonal ZrO₂ and hexagonal SiC) 25 Nd₂O₃ (e.g., ≤~94 Nd: ≤~34.0%,≥~15% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Zr:≥~1.5% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~3 wt %) Ti: ≥~5.2% Cubicand/or orthorhombic Nd₂Zr₂O₇ TiC (e.g., ≥~5 wt %) C: ≥~5.2% and/orNd₂(Zr, Ti)₂O₇ O: ≤~54.1% Monoclinic and/or tetragonal ZrO₂ Cubic and/orhexagonal TiC (e,g., at least one of monoclinic Nd₂O₃, tetragonal ZrO₂and cubic TiC; at least one of monoclinic (Nd, Zr)₂O₃, cubic Nd₂Zr₂O₇,tetragonal ZrO₂ and cubic TiC) 26 Nd₂O₃ (e.g., ≤~85 Nd: ≤~29.4%, ≥~15%Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Zr:≥~2.4% Nd₂O₃ and/or (Nd, Zr)₂O₃ ZrO₂ (e.g., ≥~5 wt %) Ti: ≥~9.7% Cubicand/or orthorhombic Nd₂Zr₂O₇ TiC (e.g., ≥~10 wt %) C: ≥~9.7% and/orNd₂(Zr, Ti)₂O₇ O: ≤~48.8% Monoclinic and/or tetragonal ZrO₂ Cubic and/orhexagonal TiC (e,g., at least one of monoclinic Nd₂O₃, tetragonal ZrO₂and cubic TiC; at least one of monoclinic (Nd, Zr)₂O₃, cubic Nd₂Zr₂O₇,tetragonal ZrO₂ and cubic TiC) 27 Nd₂O₃ (e.g., ≤~89 Nd: ≤~32.5%, ≥~15%Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50 wt %) Y: ≥~1.6%Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~3 wt %) Zr: ≥~1.5%and/or (Nd, Zr, Y)₂O₃ ZrO₂ (e.g., ≥~ 3 wt %) Ti: ≥~5.1% Cubic and/ororthorhombic Nd₂Zr₂O₇ TiC (e.g., ≥~5 wt %) C: ≥~5.1% and/or Nd₂(Zr,Ti)₂O₇ O: ≤~54.1% Monoclinic and/or tetragonal ZrO₂ Cubic and/orhexagonal TiC (e,g., at least one of monoclinic (Nd, Y)₂O₃ tetragonalZrO₂ and cubic TiC; at least one of monoclinic (Nd, Zr, Y)₂O₃, cubicNd₂Zr₂O₇, tetragonal ZrO₂ and cubic TiC) 28 Nd₂O₃ (e.g., ≤~85 Nd:≤~30.4%, ≥~15% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50wt %) Y: ≥~2.7% Nd₂O₃, Y₂O₃, (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~5 wt%) Zr: ≥~2.4% and/or (Nd, Zr, Y)₂O₃ ZrO₂ (e.g., ≥~ 5 wt %) Ti: ≥~5.0%Cubic and/or orthorhombic Nd₂Zr₂O₇ TiC (e.g., ≥~5 wt %) C: ≥~5.0% and/orNd₂(Zr, Ti)₂O₇ O: ≤~54.5% Monoclinic and/or tetragonal ZrO₂ Cubic and/orhexagonal TiC (e,g., at least one of monoclinic (Nd, Y)₂O₃ tetragonalZrO₂ and cubic TiC; at least one of monoclinic (Nd, Zr, Y)₂O₃, cubicNd₂Zr₂O₇, tetragonal ZrO₂ and cubic TiC) 29 Nd₂O₃ (e.g., ≤~88 Nd:≤~30.8%, ≥~15% Monoclinic, cubic and/or hexagonal wt %, ≥~30 wt %, ≥~50wt %) Y: ≥~1.6% Nd₂O₃, Y₂O_(3,) (Nd, Y)₂O₃, (Nd, Zr)₂O₃ Y₂O₃ (e.g., ≥~3wt %) Zr: ≥~1.4% and/or (Nd, Zr, Y)₂O₃ ZrO₂ (e.g., ≥~ 3 wt %) Si: ≥~4.4%Cubic and/or orthorhombic TiC (e.g., ≥~3 wt %) Ti: ≥~3.0% Nd₂Zr₂O₇,Nd₂(Zr, Si)₂O₇ and/or SiC (e.g., ≥~3 wt %) C: ≥~7.4% Nd₂(Zr, Ti, Si)₂O₇O: ≤~51.5% Monoclinic and/or tetragonal ZrO₂ Cubic and/or hexagonal TiCCubic and/or hexagonal SiC (e,g., at least one of monoclinic (Nd, Y)₂O₃,tetragonal ZrO₂ and cubic TiC; at least one of monoclinic (Nd, Zr,Y)₂O_(3,) cubic Nd₂(Zr, Si)₂O₇, tetragonal ZrO₂, cubic TiC and hexagonalSiC)

TABLE 4 provides examples of ceramic material compositions. A ceramicmaterial may have a composition as listed in TABLE 4. A ceramic materialmay have a composition as listed in TABLE 4 and may also compriseconstituents that are greater than or less than the amount specified inTABLE 4. For example, a constituent may be provided in a differentamount than listed in TABLE 4, one or more constituents may be added orremoved, and so on.

In an example, the ceramic material may comprise less than or equal toabout 85 wt % and/or greater than about 30 wt % Nd₂O₃, with less than orequal to about 5 wt % Y₂O₃, less than or equal to about 5 wt % ZrO₂ (orTZP) and less than or equal to about 5 wt % SiC. In this example, theceramic material may comprise Nd₂O₃, Y₂O₃, SiC, Nd₂Zr₂O₇ and/or ZrO₂crystal structures. In some instances, it may be difficult todistinguish between two or more crystal structures (e.g., Nd₂O₃ andY₂O₃) and/or other phases may not be detected (e.g., SiC and/or ZrO₂).The observed crystal structures may include, for example, monoclinicNd₂O₃ (or Y₂O₃) and/or cubic Nd₂Zr₂O₇. The ceramic material may compriseless than or equal to about 29 at % Nd and/or greater than about 15 at %Nd, and greater than or equal to about 2.5 at % Y, 2.3 at % Zr, 7.1 at %Si, 7.1 at % C and 51.9 at % 0.

In another example, the ceramic material may comprise less than or equalto about 85 wt % and/or greater than about 30 wt % Nd₂O₃, with less thanor equal to about 5 wt % Y₂O₃, greater than or equal to about 5 wt %ZrO₂ (or TZP) and greater than or equal to about 5 wt % SiC. In thisexample, the ceramic material may comprise Nd₂O₃, Y₂O₃, SiC, Nd₂Zr₂O₇and/or ZrO₂ crystal structures. The ceramic material may comprise lessthan or equal to about 29 at % Nd and/or greater than about 15 at % Nd,less than or equal to about 2.5 at % Y, and greater than or equal toabout 2.3 at % Zr, 7.1 at % Si, 7.1 at % C and 51.9 at % O.

In another example, the ceramic material may comprise less than or equalto about 75 wt % and/or greater than about 30 wt % Nd₂O₃, with less thanor equal to about 5 wt % Y₂O₃, greater than or equal to about 10 wt %ZrO₂ (or TZP) and greater than or equal to about 10 wt % SiC. In thisexample, the ceramic material may comprise Nd₂O₃, Y₂O₃, SiC, Nd₂Zr₂O₇and/or ZrO₂ crystal structures. The ceramic material may comprise lessthan or equal to about 22.7 at % Nd and/or greater than about 10 at %Nd, less than or equal to about 2.3 at % Y, and greater than or equal toabout 12.7 at % Si, 12.7 at % C, 4.1 at % Zr and 45.6 at % O.

In another example, the ceramic material may comprise less than or equalto about 90 wt % and/or greater than about 30 wt % Nd₂O₃, with greaterthan or equal to about 5 wt % ZrO₂ (or TZP) and greater than or equal toabout 5 wt % TiC. In this example, the ceramic material may compriseNd₂O₃, TiC, Nd₂Zr₂O₇ and/or ZrO₂ crystal structures. The ceramicmaterial may comprise less than or equal to about 32.9 at % Nd and/orgreater than about 15 at % Nd, and greater than or equal to about 5.1 at% Ti, 5.1 at % C, 2.5 at % Zr and 54.3 at % O.

In yet another example, the ceramic material may comprise less than orequal to about 85 wt % and/or greater than about 30 wt % Nd₂O₃, withless than or equal to about 5 wt % Y₂O₃, greater than or equal to about5 wt % ZrO₂ (or TZP) and greater than or equal to about 5 wt % TiC. Inthis example, the ceramic material may comprise Nd₂O₃, Y₂O₃, TiC,Nd₂Zr₂O₇ and/or ZrO₂ crystal structures. The ceramic material maycomprise less than or equal to about 30.4 at % Nd and/or greater thanabout 15 at % Nd, less than or equal to about 2.7 at % Y, and greaterthan or equal to about 5.0 at % Ti, 5.0 at % C, 2.4 at % Zr and 54.5 at% O.

The ceramic material may comprise Nd₂O₃. The ceramic material maycomprise a primary ceramic material (e.g., Nd₂O₃), and one or moresecondary ceramic materials (e.g., AlN). The ceramic material may besubstantially or wholly formed of the primary ceramic material. Theceramic material may comprise various levels of secondary ceramicmaterial(s). The ceramic material may comprise the secondary ceramicmaterial (e.g., AlN) at a concentration greater than or equal to about 2wt %, 5 wt % or 10 wt %. As an alternative, the ceramic material maycomprise the secondary ceramic material (e.g., AlN) at a concentrationless than about 10 wt %, 5 wt % or 2 wt %. The ceramic material maycomprise additional secondary ceramic materials (e.g., at similar ordifferent concentrations). Such additional secondary ceramic materialsmay include, for example, SiC, TiC, Y₂O₃ and/or ZrO₂.

The ceramic material may have a tensile strength or tensile yieldstrength greater than or equal to about 50 MPa, 100 MPa, 150 MPa, 200MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa, 600MPa, 700 MPa, 800 MPa, 900 MPa or 1000 MPa.

There are various examples of such ceramic material compositions. Theceramic material may comprise Nd₂O₃, and less than or equal to about 5wt % AlN (e.g., AlN particles). The ceramic material may comprise Nd₂O₃,and greater than or equal to about 2 wt %, 5 wt % or 10 wt % AlN. Theceramic material may comprise Nd₂O₃, and less than or equal to about 10wt % AlN. A ceramic comprising Nd₂O₃, and, for example, less than orequal to about 5 wt % AlN may have a CTE that closely matches (e.g.,within about 10% or less, or within less than or equal to about 0.1%,0.5%, 1%, 5%, 10%, 20% or 50%) the CTE of steel or stainless steelalloys (e.g., 430 stainless steel, 441 stainless steel, 18CrCb ferriticstainless steel, Inconel 600, ATI alloy 600 or Hastelloy S) (or anothersuitable material used instead of stainless steel, such as, for example,Ni or Fe—Ni alloys) at the operating temperature of the cell and/orsystem.

The ceramic material may comprise Y₂O₃. The ceramic material maycomprise a primary ceramic material (e.g., Y₂O₃), and one or moresecondary ceramic materials (e.g., MgO). The ceramic material may besubstantially or wholly formed of the primary ceramic material. Theceramic material may comprise various levels of secondary ceramicmaterial(s). The ceramic material may comprise the secondary ceramicmaterial (e.g., MgO) at a concentration greater than or equal to about12.5 wt %. As an alternative, the ceramic material may comprise thesecondary ceramic material (e.g., MgO) at a concentration less thanabout 12.5 wt %. The ceramic material may comprise additional secondaryceramic materials in (e.g., at similar or different concentrations). Theceramic material and/or the secondary ceramic material(s) may compriseone or more additives as described elsewhere herein.

There are various examples of such ceramic material compositions. Theceramic material may comprise Y₂O₃, and greater than or equal to about12.5 wt % MgO (e.g., MgO particles). A ceramic comprising Y₂O₃, and, forexample, greater than or equal to about 12.5 wt % MgO may have a CTEthat closely matches (e.g., within about 10% or less, or within lessthan or equal to about 0.1%, 0.5%, 1%, 5%, 10%, 20% or 50%) the CTE ofsteel or stainless steel alloys (e.g., 430 stainless steel or 439stainless steel) (or another suitable material used instead of stainlesssteel, such as, for example, Ni or Fe—Ni alloys) at the operatingtemperature of the cell and/or system.

The ceramic material may comprise AlN. The ceramic material may comprisea primary ceramic material (e.g., AlN), and one or more secondaryceramic materials (e.g., Y₂O₃, SiC, or combinations thereof). Theceramic material may be substantially or wholly formed of the primaryceramic material. The ceramic material may comprise various levels ofsecondary ceramic material(s). For example, the ceramic material maycomprise a first secondary ceramic material and a second secondaryceramic material. The ceramic material may comprise the first secondaryceramic material (e.g., Y₂O₃) at a concentration greater than or equalto about 3 wt %. As an alternative, the ceramic material may comprisethe first secondary ceramic material (e.g., Y₂O₃) at a concentrationless than about 3 wt %. The ceramic material may comprise the firstsecondary ceramic material in combination with at least the secondsecondary ceramic material (e.g., SiC), the second secondary ceramicmaterial being at a concentration greater than or equal to about 25 wt %(or 25 volume-% (also “v %,” “vol %” and “volume percent” herein). As analternative, the ceramic material may comprise the first secondaryceramic material in combination with at least the second secondaryceramic material (e.g., SiC), the second secondary ceramic materialbeing at a concentration less than about 25 wt % (or v %). In someinstances, a concentration (e.g., of a secondary ceramic material)expressed in v % may be substantially the same or similar as whenexpressed in wt % (e.g., for AlN and SiC, wt % and v % can be verysimilar). The ceramic material may comprise the second secondary ceramicmaterial without the first secondary ceramic material. The ceramicmaterial may comprise additional secondary ceramic materials (e.g., atsimilar or different concentrations). The ceramic material and/or thesecondary ceramic material(s) may comprise one or more additives asdescribed elsewhere herein. For example, the secondary ceramic material(e.g., SiC) may also comprise about 2% carbon and about 0.5% boron.

The tensile strength of the ceramic material comprising AlN and SiC(e.g., AlN+Y₂O₃+SiC) may be greater than about 400 MPa, 500 MPa, 600MPa, 700 MPa, 800 MPa or 900 MPa.

At least a portion (or all) of the second secondary ceramic material(e.g., SiC) may be present in the ceramic material as particles (e.g.,SiC particles) that are not whiskers (e.g., at least some of the SiCparticles may not be whiskers). One or more of the secondary ceramicmaterials (e.g. Y₂O₃) may function as a sintering aid.

There are various examples of such ceramic material compositions. Theceramic material may comprise AlN, and greater than or equal to about 3wt % Y₂O₃ and/or greater than or equal to about 25 wt % or volume-% SiC.The ceramic material may comprise AlN, and less than about 3 wt % Y₂O₃and/or less than about 25 wt % (or v %) SiC. The ceramic material maycomprise AlN, and greater than or equal to about 3 wt % Y₂O₃ and/or lessthan about 25 wt % (or v %) SiC. The ceramic material may comprise AlN,and less than about 3 wt % Y₂O₃ and/or greater than or equal to about 25wt % (or v %) SiC. The grain size of SiC in the ceramic material may beless than about 10 μm, 5 μm, 2 μm, 1 μm, 0.75 μm, 0.5 μm or 0.2 μm.

The ceramic material may comprise AlN. The ceramic material may comprisea primary ceramic material (e.g., AlN), and one or more secondaryceramic materials (e.g., Y₂O₃, Nd₂O₃, SiC, TiC, or any combinationthereof). The ceramic material may be substantially or wholly formed ofthe primary ceramic material. The ceramic material may comprise variouslevels of secondary ceramic material(s). For example, the ceramicmaterial may comprise a first secondary ceramic material and a secondsecondary ceramic material. The ceramic material may comprise the firstsecondary ceramic material (e.g., Nd₂O₃) at a concentration greater thanor equal to about 1 wt %, 3 wt %, 5 wt % or 10 wt %. As an alternative,the ceramic material may comprise the first secondary ceramic material(e.g., Nd₂O₃) at a concentration less than about 10 wt %, 3 wt %, 5 wt %or 1 wt %, of. The ceramic material may comprise the first secondaryceramic material in combination with at least the second secondaryceramic material (e.g., Y₂O₃, SiC or TiC), the second secondary ceramicmaterial being at a concentration greater than or equal to about 5 wt %(or v %), 10 wt % (or v %), 15 wt % (or v %), 20 wt % (or v %), 25 wt %(or v %), 30 wt % (or v %) or 40 wt % (or v %). As an alternative, theceramic material may comprise the first secondary ceramic material incombination with at least the second secondary ceramic material (e.g.,Y₂O₃, SiC or TiC), the second secondary ceramic material being at aconcentration less than about 40 wt % (or v %), 30 wt % (or v %), 25 wt% (or v %), 20 wt % (or v %), 15 wt % (or v %), 10 wt % (or v %) or 5 wt% (or v %). In some instances, a concentration (e.g., of a secondaryceramic material) expressed in v % may be substantially the same orsimilar as when expressed in wt % (e.g., for AlN and SiC, wt % and v %can be very similar). The ceramic material may comprise the secondsecondary ceramic material without the first secondary ceramic material.The first secondary material may be selected, for example, among theaforementioned one or more secondary materials (e.g., Y₂O₃, SiC or TiCmay be selected instead of Nd₂O₃). The second secondary material maythen be suitably selected from the remainder of the one or moresecondary ceramic materials. The ceramic material may compriseadditional secondary ceramic materials (e.g., at similar or differentconcentrations). The ceramic material and/or the secondary ceramicmaterial(s) may comprise one or more additives as described elsewhereherein. During processing (e.g., sintering) the primary ceramic materialand at least one of the secondary ceramic materials may react to form anew phase (e.g., Nd₂AlNO₃), and/or the primary ceramic material and atleast one additive may react to form a new phase. Secondary ceramicmaterials may or may not react with each other.

The second secondary ceramic material may have a smaller grain size thaneither the first ceramic material and/or other secondary ceramicmaterial(s). In an example, the second secondary ceramic material is SiCor TiC and the particle size of the SiC to TiC particles in the ceramicis less than or equal to about 10 μm, 5 μm, 2 μm, 1 μm, 0.7 μm, 0.5 μm,0.45 μm, 0.1 μm or 0.01 μm. In another example, the ceramic materialcomprises AlN, about 5 wt % Nd₂O₃, and about 5 wt % SiC or TiC where theSiC or TiC particle size is about 0.7 μm or 0.45 μm, and Nd₂O₃ materialhas reacted with AlN material to form Nd₂AlNO₃.

At least a portion (or all) of the second secondary ceramic material(e.g., SiC) may be present in the ceramic material as particles (e.g.,SiC particles) that are not whiskers (e.g., at least some of the SiCparticles may not be whiskers). One or more of the secondary ceramicmaterials (e.g. Y₂O₃) may function as a sintering aid.

The ceramic material (e.g., AlN+Nd₂O₃+SiC or AlN+Nd₂O₃+TiC, e.g., AlN+5wt % Nd₂O₃+5 wt % SiC) may have a tensile yield strength greater than orequal to about 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa, 600MPa, 700 MPa, 800 MPa, 900 MPa, 1000 MPa, 1200 MPa, 1400 MPa, 1600 MPa,1800 MPa or 2000 MPa. The MC fracture toughness of the ceramic material(e.g., AlN+5 wt % Nd₂O₃+5 wt % SiC) may be greater than or equal toabout 5 MPa-m^(1/2), 6 MPa-m^(1/2), 7 MPa-m^(1/2), 8 MPa-m^(1/2), 9MPa-m^(1/2), 10 MPa-m^(1/2), 11 MPa-m^(1/2), 12 MPa-m^(1/2), 13MPa-m^(1/2), 14 MPa-m^(1/2) or 15 MPa-m^(1/2) (as measured through microhardness indentation tests). The ceramic material may have such strengthand/or fracture toughness, for example, when the particle size of thesecond secondary ceramic material is less than or equal to about 10 μm,5 μm, 2 μm, 1 μm, 0.7 μm, 0.5 μm, 0.45 μm, 0.1 μm, 0.01 μm or less.

There are various examples of such ceramic material compositions. Theceramic material may comprise AlN, and greater than or equal to about 3wt % Nd₂O₃ and/or greater than or equal to about 5 wt % (or v %) SiC orTiC. The ceramic material may comprise AlN, and less than or equal toabout 10 wt % Nd₂O₃ and/or less than or equal to about 40 wt % (or v %)SiC or TiC. The ceramic material may comprise AlN, and greater than orequal to about 1 wt % Nd₂O₃ and/or less than or equal to about 40 wt %(or v %) SiC or TiC. The ceramic material may comprise AlN, and lessthan or equal to about 10 wt % Nd₂O₃ and/or greater than or equal toabout 5 wt % (or v %) SiC. In an example, the ceramic material comprisesAlN, and about 5 wt % Nd₂O₃ and/or about 25 wt % (or v %) SiC or TiC.

Some examples of ceramic material compositions comprising AlN areprovided in TABLE 5. Examples of raw materials with amounts/levels, andatomic percentages (including oxygen and carbon atoms) are provided inthe same format as in TABLE 4. The first ceramic material constituent ineach row in the “Ceramic constituents” column may be considered theprimary ceramic material (e.g., AlN), and all other ceramic materials inthe row may be considered secondary ceramic materials. The primaryceramic material (e.g., AlN) may form greater than or equal to about 30wt %, 40 wt %, 50 wt % or 60 wt % of the ceramic material for thecompositions listed in TABLE 5 (e.g., the primary ceramic material mayform greater than about 30 wt %, 40 wt %, 50 wt % or 60 wt % of thefinal ceramic material). Further details regarding the format of TABLE 5are provided in relation to TABLE 4 and accompanying description. Adiscussion of crystal structures is provided below.

TABLE 5 EXAMPLES OF CERAMIC MATERIAL COMPOSITIONS Atomic percentages #Ceramic Constituents (wt %) examples/ranges 1 AlN (e.g., ≤~97 wt %, ≥~30Al: ≤~49.3%, ≥~25% wt %, ≥~50 wt %) N: ≤~49.3%, ≥~25% Y₂O₃ (e.g., ≥~3 wt%) Y: ≥~0.6% O: ≥~0.8% 2 AlN (e.g., ≤~97 wt %, ≥30 Al: ≤~49.5%, ≥~25% wt%, ≥50 wt %) N: ≤~49.5%, ≥~25% Nd₂O₃ (e.g., ≥~3 wt %) Nd: ≥~0.4% O:≥~0.6% 3 AlN (e.g., ≤~95 wt %, ≥~30 Al: ≤~47.4%, ≥~20% wt %, ≥~50 wt %)N: ≤~47.4%, ≥~20% SiC (e.g., ≥~5 wt %) Si: ≥~2.6% C: ≥~2.6% 4 AlN (e.g.,≤~95 wt %, ≥~30 Al: ≤~48.3%, ≥~20% wt %, ≥~50 wt %) N: ≤~48.3%, ≥~20%TiC (e.g., ≥~5 wt %) Ti: ≥~1.7% C: ≥~1.7% 5 AlN (e.g., ≤~72 wt %, ≥~30Al: ≤~36.4%, ≥~20% wt %, ≥~50 wt %) N: ≤~36.4%, ≥~20% Y₂O₃ (e.g., ≥~3 wt%) Y: ≥~0.6% SiC (e.g., ≥~25 wt %) O: ≥~0.8% Si: ≥~12.9% C: ≥~12.9% 6AlN (e.g., ≤~87 wt %, ≥~30 Al: ≤~44.1%, ≥~20% wt %, ≥~50 wt %) N:≤~44.1%, ≥~20% Y₂O₃ (e.g., ≥~3 wt %) Y: ≥~0.6% SiC (e.g., ≥~10 wt %) O:≥~0.8% Si: ≥~5.2% C: ≥~5.2% 7 AlN (e.g., ≤~82 wt %, ≥~30 Al: ≤~41.5%,≥~20% wt %, ≥~50 wt %) N: ≤~41.5%, ≥~20% Y₂O₃ (e.g., ≥~3 wt %) Y: ≥~0.6%SiC (e.g., ≥~15 wt %) O: ≥~0.8% Si: ≥~7.8% C: ≥~7.8% 8 AlN (e.g., ≤~77wt %, ≥~30 Al: ≤~39.0%, ≥~20% wt %, ≥~50 wt %) N: ≤~39.0%, ≥~20% Y₂O₃(e.g., ≥~3 wt %) Y: ≥~0.6% SiC (e.g., ≥~20 wt %) O: ≥~0.8% Si: ≥~10.3%C: ≥~10.3% 9 AlN (e.g., ≤~70 wt %, ≥~30 Al: ≤~36.9%, ≥~20% wt %, ≥~50 wt%) N: ≤~36.9%, ≥~20% Y₂O₃ (e.g., ≥~10 wt %) Y: ≥~1.9% SiC (e.g., ≥~20 wt%) O: ≥~2.9% Si: ≥~10.8% C: ≥~10.8% 10 AlN (e.g., ≤~91 wt %, ≥~30 Al:≤~46.6%, ≥~20% wt %, ≥~50 wt %) N: ≤~46.2%, ≥~20% Al₂O₃ (e.g., ≤~1 wt %)Y: ≥~0.6% Y₂O₃ (e.g., ≥~3 wt %) O: ≥~1.4% SiC (e.g., ≥~5 wt %) Si:≥~2.6% C: ≥~2.6% 11 AlN (e.g., ≤~89 wt %, ≥~30 Al: ≤~45.6%, ≥~20% wt %,≥~50 wt %) N: ≤~45.2%, ≥~20% Al₂O₃ (e.g., ≤~1 wt %) Y: ≥~0.6% Y₂O₃(e.g., ≥~3 wt %) O: ≥~1.4% SiC (e.g., ≥~7 wt %) Si: ≥~3.6% C: ≥~3.6% 12AlN (e.g., ≤~86 wt %, ≥~30 Al: ≤~44.0%, ≥~20% wt %, ≥~50 wt %) N:≤~43.6%, ≥~20% Al₂O₃ (e.g., ≤~1 wt %) Y: ≥~0.6% Y₂O₃ (e.g., ≥~3 wt %) O:≥~1.4% SiC (e.g., ≥~10 wt %) Si: ≥~5.2% C: ≥~5.2% 13 AlN (e.g., ≤~76 wt%, ≥~30 Al: ≤~38.9%, ≥~20% wt %, ≥~50 wt %) N: ≤~38.5%, ≥~20% Al₂O₃(e.g., ≤~1 wt %) Y: ≥~0.6% Y₂O₃ (e.g., ≥~3 wt %) O: ≥~1.4% SiC (e.g.,≥~20 wt %) Si: ≥~10.3% C: ≥~10.3% 14 AlN (e.g., ≤~94 wt %, ≥~30 Al:≤~48.8%, ≥~25% wt %, ≥~50 wt %) N: ≤~48.8%, ≥~25% Y₂O₃ (e.g., ≥~3 wt %)Y: ≥~0.6% Nd₂O₃ (e.g., ≥~3 wt %) Nd: ≥~0.4% O: ≥~1.4% 15 AlN (e.g., ≤~85wt %, ≥~30 Al: ≤~47.6%, ≥~25% wt %, ≥~50 wt %) N: ≤~47.6%, ≥~25% Y₂O₃(e.g., ≥~3 wt %) Y: ≥~0.6% Nd₂O₃ (e.g., ≥~10 wt %) Nd: ≥~1.3% O: ≥~2.9%16 AlN (e.g., ≤~92 wt %, ≥~30 Al: ≤~46.9%, ≥~20% wt %, ≥~50 wt %) N:≤~46.9%, ≥~20% Nd₂O₃ (e.g., ≥~3 wt %) Nd: ≥~0.4% SiC (e.g., ≥~5 wt %) O:≥~0.6% Si: ≥~2.6% C: ≥~2.6% 17 AlN (e.g., ≤~87 wt %, ≥~30 Al: ≤~44.3%,≥~20% wt %, ≥~50 wt %) N: ≤~44.3%, ≥~20% Nd₂O₃ (e.g., ≥~3 wt %) Nd:≥~0.4% SiC (e.g., ≥~10 wt %) O: ≥~0.6% Si: ≥~5.2% C: ≥~5.2% 18 AlN(e.g., ≤~72 wt %, ≥~30 Al: ≤~36.6%, ≥~20% wt %, ≥~50 wt %) N: ≤~36.6%,≥~20% Nd₂O₃ (e.g., ≥~3 wt %) Nd: ≥~0.4% SiC (e.g., ≥~25 wt %) O: ≥~0.6%Si: ≥~13.0% C: ≥~13.0% 19 AlN (e.g., ≤~80 wt %, ≥~30 Al: ≤~42.9%, ≥~20%wt %, ≥~50 wt %) N: ≤~42.9%, ≥~20% Nd₂O₃ (e.g., ≥~10 wt %) Nd: ≥~1.3%SiC (e.g., ≥~10 wt %) O: ≥~2.0% Si: ≥~5.5% C: ≥~5.5% 20 AlN (e.g., ≤~70wt %, ≥~30 Al: ≤~40.6%, ≥~20% wt %, ≥~50 wt %) N: ≤~40.6%, ≥~20% Nd₂O₃(e.g., ≥~20 wt %) Nd: ≥~2.6% SiC (e.g., ≥~10 wt %) O: ≥~4.2% Si: ≥~5.9%C: ≥~5.9% 21 AlN (e.g., ≤~87 wt %, ≥~30 Al: ≤~45.8%, ≥~20% wt %, ≥~50 wt%) N: ≤~45.8%, ≥~20% Y₂O₃ (e.g., ≥~3 wt %) Y: ≥~0.6% Nd₂O₃ (e.g., ≥~5 wt%) Nd: ≥~0.6% SiC (e.g., ≥~5 wt %) O: ≥~1.8% Si: ≥~2.7% C: ≥~2.7% 22 AlN(e.g., ≤~77 wt %, ≥~30 Al: ≤~42.0%, ≥~20% wt %, ≥~50 wt %) N: ≤~42.0%,≥~20% Y₂O₃ (e.g., ≥~3 wt %) Y: ≥~0.6% Nd₂O₃ (e.g., ≥~10 wt %) Nd: ≥~1.3%SiC (e.g., ≥~10 wt %) O: ≥~2.9% Si: ≥~5.4% C: ≥~5.4% 23 AlN (e.g., ≤~92wt %, ≥~30 Al: ≤~47.5%, ≥~20% wt %, ≥~50 wt %) N: ≤~47.5%, ≥~20% Y₂O₃(e.g., ≥~3 wt %) Y: ≥~0.6% TiC (e.g., ≥~5 wt %) O: ≥~0.8% Ti: ≥~1.8% C:≥~1.8% 24 AlN (e.g., ≤~92 wt %, ≥~30 Al: ≤~47.7%, ≥~20% wt %, ≥~50 wt %)N: ≤~47.7%, ≥~20% Nd₂O₃ (e.g., ≥~3 wt %) Nd: ≥~0.4% TiC (e.g., ≥~5 wt %)O: ≥~0.6% Ti: ≥~1.8% C: ≥~1.8% 25 AlN (e.g., ≤~87 wt %, ≥~30 Al:≤~46.6%, ≥~20% wt %, ≥~50 wt %) N: ≤~46.6%, ≥~20% Y₂O₃ (e.g., ≥~3 wt %)Y: ≥~0.6% Nd₂O₃ (e.g., ≥~5 wt %) Nd: ≥~0.7% TiC (e.g., ≥~5 wt %) O:≥~1.9% Ti: ≥~1.8% C: ≥~1.8% 26 AlN (e.g., ≤~73 wt %, ≥~30 Al: ≤~41.5%,≥~20% wt %, ≥~50 wt %) N: ≤~41.5%, ≥~20% Y₂O₃ (e.g., ≥~3 wt %) Y: ≥~0.6%Nd₂O₃ (e.g., ≥~10 wt %) Nd: ≥~1.4% TiC (e.g., ≥~15 wt %) O: ≥~3.1% Ti:≥~5.9% C: ≥~5.9% 27 AlN (e.g., ≤~92 wt %, ≥30 Al: ≤~47.7%, ≥~20% wt %,≥50 wt %) N: ≤~47.7%, ≥~20% Nd₂O₃ (e.g., ≥~3 wt %) Nd: ≥~0.4% TiC (e.g.,≥~5 wt %) O: ≥~0.6% Ti: ≥~1.8% C: ≥~1.8% 28 AlN (e.g., ≤~87 wt %, ≥30Al: ≤~45.9%, ≥~20% wt %, ≥50 wt %) N: ≤~45.9%, ≥~20% Nd₂O₃ (e.g., ≥~3 wt%) Nd: ≥~0.4% TiC (e.g., ≥~10 wt %) O: ≥~0.6% Ti: ≥~3.6% C: ≥~3.6%

The crystal structure of ceramic materials with AlN as the primaryceramic component may include one or more crystal structures based onthe compounds used to fabricate the ceramic material (e.g., ceramicconstituents), as well as phases that may form based on interactionsbetween the various ceramic constituents. Ceramic compositionscomprising AlN and Y₂O₃ may comprise, for example, hexagonal (e.g.,wurtzite) AlN and/or cubic or monoclinic Y₂O₃. In some cases, traceamounts of trigonal Al₂O₃ may be present due to residual amounts on thesurface of AlN used to fabricate sintered ceramic materials, resultingin additional yttria-alumina phases such as, for example, orthorhombicYAP (YAlO₃), cubic YAG (Y₃Al₅O₁₂) and/or monoclinic YAM (Y₄Al₂O₉).Ceramic compositions comprising AlN and Nd₂O₃ may comprise, for example,hexagonal AlN, hexagonal or monoclinic Nd₂O₃ and/or tetragonal Nd₂AlNO₃.In some cases, AlN used to fabricate ceramics may also contain smallamounts of Al₂O₃, which may cause ceramics fabricated from AlN and Nd₂O₃to form an additional rhombohedral Nd(AlO₃) crystal structure. Ceramiccompositions comprising SiC and/or TiC secondary ceramic components(e.g., other ceramic compositions comprising SiC and/or TiC secondaryceramic components) may (e.g., also) include, for example, hexagonal SiCand/or cubic TiC crystal structures. SiC or TiC may also react withNd₂O₃ to form SiO₂, TiO₂ and/or NdC₂. In an example, the ceramicmaterial may comprise AlN (e.g., greater than about 30 wt % AlN), atleast about 5 vol % or 20 vol % SiC, and at least about 5 wt % Nd₂AlNO₃.The Nd₂AlNO₃ may be formed, for example, as a result of reaction of AlNwith Nd₂O₃. Such a composition of crystal structures/phases (or at leasta subset thereof) may result from sintering and/or may be used as a rawmaterial.

In an example, the ceramic material may comprise less than or equal toabout 72 wt % and greater than about 50 wt % AlN, greater than or equalto about 3 wt % Y₂O₃, and greater than or equal to about 25 wt % SiC. Inthis example, the ceramic material may comprise less than or equal toabout 36.4 at % Al and/or greater than about 15 at % Al, less than orequal to about 36.4 at % N and/or greater than about 20 at % N, greaterthan or equal to about 0.6 at % Y, greater than or equal to about 0.8 at% O, greater than or equal to about 12.9 at % Si, and greater than orequal to about 12.9 at % C. The ceramic material may comprise hexagonalAlN, orthorhombic YAP, cubic YAG, monoclinic YAM, monoclinic Y₂O₃ and/orhexagonal SiC.

In another example, the ceramic material may comprise less than or equalto about 72 wt % and greater than about 50 wt % AlN, greater than orequal to about 3 wt % Nd₂—O₃, and greater than or equal to about 25 wt %SiC. In this example, the ceramic material may comprise less than orequal to about 36.6 at % Al and/or greater than about 20 at % Al, lessthan or equal to about 36.6 at % N and/or greater than about 20 at % N,greater than or equal to about 0.4 at % Nd, greater than or equal toabout 0.6 at % O, greater than or equal to about 13.0 at % Si, andgreater than or equal to about 13.0 at % C. The ceramic material maycomprise hexagonal AlN, hexagonal or monoclinic Nd₂O₃, Nd₂AlNO₃ and/orhexagonal SiC.

In yet another example, the ceramic material may comprise less than orequal to about 92 wt % and greater than about 50 wt % AlN, greater thanor equal to about 3 wt % Nd₂O₃, and greater than or equal to about 5 wt% TiC. In this example, the ceramic material may comprise less than orequal to about 47.7 at % Al and/or greater than about 20 at % Al, lessthan or equal to about 47.7 at % N and/or greater than about 20 at % N,greater than or equal to about 0.4 at % Nd, greater than or equal toabout 0.6 at % 0, greater than or equal to about 1.8 at % Ti, andgreater than or equal to about 1.8 at % C. The ceramic material maycomprise hexagonal AlN, hexagonal or monoclinic Nd₂O₃, Nd₂AlNO₃ and/orcubic TiC.

The primary and/or secondary ceramic material may comprise grains ofceramic material(s) (e.g., neodymium oxide, aluminum nitride, siliconcarbide, silicon nitride, magnesium oxide, zirconium oxide or yttriumoxide) that are less than or equal to about 0.01 micrometers (μm), 0.05μm, 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8μm, 9 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm,90 μm, 100 μm, 150 μm, 200 μm, 400 μm, 500 μm or 1,000 μm in size. Theprimary and/or secondary ceramic material may comprise grains of ceramicmaterial(s) that are greater than about 0.1 μm, 0.2 μm, 0.5 μm, 1 μm, 2μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 30μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm,400 μm, 500 μm or 1,000 μm in size. The primary and/or secondary ceramicmaterial may comprise grains of ceramic material(s) between about 0.1 μmand 5 μm, 1 μm and 5 μm, 2 μm and 4 μm, 2 μm and 10 μm, 10 μm and 40 μm,20 μm and 100 μm, 100 μm and 500 μm, 0.1 μm and 1,000 μm, or 1 μm and1000 μm in size. Grain size may refer to diameter, length, width or anyother dimension of a grain (e.g., grains may be less than about 1 μm insize).

After densifying the ceramic though one or more processes (e.g., sinter,HIP process, hot press process, or sinter and HIP process), the ceramicmay comprise grains of the primary and/or secondary ceramic material(s)that have an atomic configuration (e.g., crystal structure) consistentwith a phase that is the most thermodynamically stable phase at roomtemperature. After densifying the ceramic though one or more processes(e.g., HIP, hot press process, or sinter and HIP process), the ceramicmay comprise grains or portions of grains of the primary and/orsecondary ceramic material(s) that have an atomic configuration (e.g.,crystal structure) consistent with a phase that is different than themost thermodynamically stable phase at room temperature. For example,the combination of materials (composition) and densification process mayresult in a ceramic material that comprises grains or portions of grainsof the primary or secondary ceramic material in a phase (e.g., crystalstructure) that is different than the phase that is mostthermodynamically stable at room temperature. The ceramic may compriseone or more phases of the primary and/or secondary ceramic material(s)(e.g., for each primary or secondary ceramic material, the ceramicmaterial may comprise the most thermodynamically stable phase and/or oneor more phases different from the most thermodynamically stable phase).

The phase that is different than the most thermodynamically stable phaseat room temperature may in some cases correspond to a given phase (e.g.,the most thermodynamically stable phase) at a temperature other than theroom temperature (e.g., at a higher temperature). Such a phase may bestabilized using suitable composition and process. For example, a highertemperature Nd₂O₃ phase may be stabilized in a monoclinic Nd₂O₃ crystalstructure. In some examples, stabilizing a crystal structure that is notthe most thermodynamically stable crystal structure at room temperaturemay improve the stability of the ceramic material (e.g., improve itschemical stability against corrosion from water or moist air, improveits stability with reactive material, improve its stability in air athigh temperature and in moist air at room temperature, etc.). Forexample, the crystal structure of Nd₂O₃ that is the mostthermodynamically stable at room temperature may be the hexagonalcrystal structure. At suitable composition and densification condition,a ceramic comprising Nd₂O₃ and other secondary ceramic materials (e.g.,Y₂O₃ and/or SiC) may result in a ceramic material comprising Nd₂O₃grains that are configured in a monoclinic crystal structure (e.g.,yttria stabilized neodymia). In some examples, a ceramic materialcomprising Nd₂O₃ grains in the monoclinic crystal structure may be morestable in the presence of air, moist air and/or water (e.g., may notcrumble in air at room temperature due to moisture).

Primary and/or secondary material(s) with such grain size(s) may beprovided in one or more ceramic materials of the disclosure. Forexample, the ceramic material of the seal can comprise Nd₂O₃, andgreater than about 5 wt % AlN, with grains that are about 2 μm to 4 μmin size. The primary ceramic material may have a different grain sizethan one or more of the secondary materials. The grain size (e.g.,diameter, radius, thickness, width, length or another characteristicgrain dimension) may refer to a grain size of the primary or secondarymaterial(s) individually (e.g., the size of atomically aligned regionsof the ceramic). Ceramic materials comprising grains may in some casesbe compacted (e.g., pressed). Morphology and/or particle sizedistribution of the primary and/or secondary ceramic material may bemodified using, for example, high energy milling and/or differentmixing/milling methods (e.g., ball milling, high energygrinding/milling, attrition milling, planetary mixing or centrifugalmixing).

CTE-matching characteristics may depend on composition (e.g., identityand amount of primary and secondary material(s)), morphology (e.g.,grain size and distribution of each of primary and secondarymaterial(s)) and/or other factors (e.g., mechanical processing, castingor shaping/forming). In an example, a ceramic material comprising Nd₂O₃,and greater than or equal to about 5 wt % AlN, with about 2 micrometerto 4 micrometer grain size, may have a CTE that is substantially similaror nearly identical to 430 SS, 18CrCb ferritic stainless steel and/or441 stainless steel. In another example, a ceramic material comprisingNd₂O₃, and greater than or equal to about 3 wt % Y₂O₃ and/or greaterthan or equal to about 5 wt % SiC or TiC, with about 0.01 micrometer to20 micrometer grain size, may have a CTE that is substantially similaror nearly identical to a Ni alloy (e.g., alloy 42 or alloy 52) or astainless steel (e.g., 430 stainless steel, 18CrCb ferritic stainlesssteel or 441 stainless steel).

Examples of primary ceramic materials and/or secondary ceramic materialsmay include any ceramic material described herein, such as, for example,aluminum nitride (AlN), beryllium nitride (Be₃N₂), boron nitride (BN),calcium nitride (Ca₃N₂), silicon nitride (Si₃N₄), aluminum oxide(Al₂O₃), beryllium oxide (BeO), calcium oxide (CaO), cerium oxide(Ce₂O₃), erbium oxide (Er₂O₃), lanthanum oxide (La₂O₃), magnesium oxide(MgO), neodymium oxide (Nd₂O₃), samarium oxide (Sm₂O₃), scandium oxide(Sc₂O₃), ytterbium oxide (Yb₂O₃), yttrium oxide (Y₂O₃), zirconium oxide(ZrO₂), yttria partially stabilized zirconia (YPSZ), boron carbide(B₄C), silicon carbide (SiC), titanium carbide (TiC), zirconium carbide(ZrC), titanium diboride (TiB₂), chalcogenides, quartz, glass, or anycombination thereof.

The ceramic material (e.g., one or more ceramic materials comprisingNd₂O₃, such as, for example, listed in TABLE 4) may retain mechanicalstrength after exposure to air at a temperature of at least about 20°C., 100° C., 200° C., 300° C., 400° C., 500° C., 600° C., 700° C., 800°C. or 900° C. (e.g., at an operating temperature of a high temperaturereactive material device) for at least about 1 hour (h), 5 h, 10 h, 1day, 2 days, 3 days, 4 days, 100 h, 5 days, 7 days, 10 days, 2 weeks, 1month, 2 months, 6 months, 9 months, 1 year, 2 years, 3 years, 4 years,5 years, 10 years or more. The ceramic material (e.g., one or moreceramic materials comprising Nd₂O₃, such as, for example, listed inTABLE 4) may retain mechanical strength after being submerged in areactive material (e.g., lithium metal-saturated molten LiCl—LiBr—LiFsalts) at a temperature of at least about 20° C., 100° C., 200° C., 300°C., 400° C., 500° C., 600° C., 700° C., 800° C. or 900° C. (e.g., at anoperating temperature of a high temperature reactive material device)for at least about 1 minute, 5 minutes, 10 minutes, 20 minutes, 30minutes, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 1 day, 2days, 3 days, 4 days, 5 days, 7 days, 10 days, 2 weeks, 1 month, 2months, 6 months, 9 months, 1 year, 2 years, 3 years, 4 years, 5 yearsor more. The ceramic material (e.g., one or more ceramic materialscomprising Nd₂O₃, such as, for example, listed in TABLE 4) may retainmechanical strength after being submerged in water at a temperature ofat least about 25° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C. or100° C. for at least about 1 h, 5 h, 10 h, 1 day, 2 days, 3 days, 4days, 100 h, 5 days, 7 days, 10 days, 2 weeks, 1 month, 2 months, 6months, 9 months, 1 year, 2 years, 3 years, 4 years, 5 years, 10 yearsor more. Mechanical strength may be retained, for example, to withinabout 1%, 2%, 5%, 10%, 20%, 30%, 40% or 50% of initial value.

While such ceramic materials may be described herein primarily in thecontext of seals (e.g., the ceramic materials described in the contextof TABLE 4 and TABLE 5 may be used, for example in seals of FIG. 12,FIG. 13, FIG. 14, FIG. 15, FIG. 16, FIG. 17, FIG. 18, FIG. 19, FIG. 20,FIG. 21, FIG. 30, FIG. 35, FIG. 36, FIG. 37, FIG. 38, FIG. 40 and/orFIG. 41), the ceramic materials can be used in other applications. Suchapplications may be as described elsewhere herein (e.g., in relation toreactor vessel linings). Examples of applications may includeapplications that utilize or depend on one or more characteristics orproperties of such ceramic materials (e.g., strength, air stability,corrosion resistance and/or other characteristics/properties describedherein). In an example, stronger ceramic materials (e.g., ceramicmaterials comprising AlN, such as, for example, AlN+Nd₂O₃+SiC orAlN+Nd₂O₃+TiC) may be used in bullet-proof vests. In another example, aceramic material (e.g., AlN+3 wt % Y₂O₃ and at least about 25 vol % SiC,or AlN+at least about 3 wt % Nd₂O₃+at least about 5 vol % or 20 vol %SiC) may be used in a device that protects against ballisticpenetration, such as, for example, ballistic armor.

The braze can be a passive braze or an active braze. Passive brazes canmelt and wet a ceramic material or wet a ceramic material that has ametallization layer deposited onto it. Copper and silver are examples ofpassive brazes. Active brazes can react with the ceramic (e.g.,chemically reduce the metal component of the ceramic (e.g., Al isreduced from AlN)). In some cases, active brazes can comprise a metalalloy having an active metal species such as titanium (Ti) or zirconium(Zr) that reacts with the ceramic material (e.g., AlN+Ti→Al+TiN orAlN+Zr→Al+ZrN). The active braze can further comprise one or morepassive components (e.g., Ni). The passive component(s) can, forexample, reduce the melting point of the braze and/or improve thechemical stability of the braze. In some cases, the active metal brazebeads up on the ceramic and/or does not wet the ceramic.

The seal can hermetically seal the electrochemical cell. In some cases,the seal is inert to an atmosphere in contact with the electrochemicalcell. The atmosphere in contact with the electrochemical cell cancomprise oxygen (O₂), nitrogen (N₂), water (H₂O), or a combinationthereof. In some cases, the ceramic material, metal sleeve or collarmaterial, and/or the braze material are coated to provide resistance tothe atmosphere (e.g., air stability) in contact with the electrochemicalcell. For example, the coating can comprise silicon dioxide (SiO₂),yttrium oxide (Y₂O₃), aluminum oxide (Al₂O₃), phosphate glass (e.g.,P₂O₅), aluminophosphate glass (e.g., AlPO₄, doped AlPO₄, AlPO₄comprising small (e.g., nanoscale/nanometer scale) carbon particles(e.g., encapsulated within the aluminophosphate glass), aluminophosphatecomprising Al—O—Al bonds, amorphous aluminophosphate glass that resistscrystallization above at least 800° C.), or any combination thereof. Insome cases, the coating may form a transparent thin film.

The seal can be at least partially inert to metal vapors and moltensalts. In some cases, the metal vapors comprise lithium, sodium,potassium, magnesium, calcium, or any combination thereof. The ceramicmaterial and/or the braze material can be coated to provide resistanceto the metal vapors and metal salts. For example, the coating can beyttrium oxide (Y₂O₃), erbium oxide (Er₂O₃), boron nitride (BN), aluminumnitride (AlN), silicon nitride (Si₃N₄), silicon carbide (SiC), or anycombination thereof.

In some cases, the coefficients of thermal expansion of the ceramicmaterial and the braze material match the coefficients of thermalexpansion of the electrically conductive housing and/or the conductor(e.g., to within about 1%, 5%, 10%, 15%, 20% or 30%). In some cases, ahermetic joint can be formed if the braze is not of a similar CTEcompared with the CTE of the ceramic and/or other components orsub-assembly of the seal (e.g., a metal sleeve).

The seal can be welded or brazed to the electrically conductive housing,cell (housing) lid, and/or the conductor. In some cases, theelectrically conductive housing and/or the conductor comprises400-series stainless steel, 300-series stainless steel, nickel, or anycombination thereof

FIG. 7 shows the CTE in units of parts per million (ppm) per ° C. forvarious types of steel and an insulating ceramic. The CTE for 430stainless steel 705 can range approximately linearly from about 10 ppm/°C. to about 12 ppm/° C. between about 250° C. and 800° C. The CTE fornickel-cobalt ferrous alloy 710 can range non-linearly from about 5ppm/° C. to about 10 ppm/° C. between about 250° C. and 800° C. The CTEfor aluminum nitride ceramic 715 can be relatively constant at about 4.5ppm/° C. between about 250° C. and 800° C.

FIG. 8 shows the CTE in units of parts (p) per ° C. for various types ofsleeve or collar materials (e.g., steel), braze materials and insulatingceramics. The sleeve or collar materials can include, for example, 304stainless steel 805, 430 stainless steel 810, 410 stainless steel 815,and nickel-cobalt ferrous alloy 820. The braze materials can include,for example, nickel-100 825, molybdenum (Mo) 830 and tungsten (W) 835.The ceramic materials can include, for example, aluminum nitride (AlN)840, aluminum oxide (Al₂O₃) 845, boron nitride (BN) in the directionparallel to the grain orientation 850, boron nitride (BN) in thedirection perpendicular to the grain orientation 855, yttrium oxide(Y₂O₃) 860 and yttria partially stabilized zirconia (YPSZ) 865.

The CTE of the seal can match the CTE of the housing and/or conductor toany suitable tolerance. In some cases, the seal electrically isolatesthe conductor from the electrically conductive housing, where the CTE ofthe seal is at least about 1%, 5%, 10%, 15%, 20%, 30%, 50%, 60%, 70% or80% different and/or less than the CTE of the electrically conductivehousing and/or the conductor. In some instances, the seal electricallyisolates the conductor from the electrically conductive housing, wherethe CTE of the seal is less than about 1%, 5%, 10%, 15%, 20%, 30%, 50%,60%, 70% or 80% different and/or less than the CTE of the electricallyconductive housing and/or the conductor.

The CTE of the seal can be matched to the conductive housing or theconductor at the operating temperature and/or during start-up of thecell (e.g., starting from non-molten metal electrodes). In some cases,the CTE of the seal is less than about 5%, 10%, 15% or 20% differentthan the CTE of the electrically conductive housing and/or the conductorat the temperature at which the electrochemical cell is operated. Insome instances, the CTE of the seal is less than about 5%, 10%, 15% or20% different than the CTE of the electrically conductive housing and/orthe conductor at all temperatures between about −10° C. and theoperating temperature.

The materials comprising the seal (e.g., ceramic insulator, braze alloy,and sleeve/collar) can be chosen to be chemically compatible with (e.g.,stable in contact with) the interior and/or exterior environments of thecell.

FIG. 9 shows the Gibbs free energy of formation (ΔG_(r)) for variousmaterials at a range of temperatures with negative numbers being morethermodynamically stable 905. Examples include ΔG_(r) curves for lithiumnitride (Li₃N) 910, aluminum nitride (AlN) 915 and titanium nitride(TiN) 920. A thermodynamic evaluation of different insulating ceramicmaterials can indicate that aluminum nitride (an electrically insulatingceramic) can be stable in the presence of lithium (e.g., since theΔG_(r) per mole of N of AlN is more negative than Li₃N). Also, theΔG_(r) per mole of N of TiN is more negative than Li₃N and also morenegative than AlN. Thus, a titanium-alloy braze can chemically reduceAlN and form TiN (e.g., by the reaction AlN+Ti→TiN+Al), which, in turn,can bond well with the titanium-alloy braze. The reactive material(e.g., reactive metal), ceramic and braze materials can be selected suchthat the stability (e.g., normalized Gibbs free energy of formation(ΔG_(r),n), such as, for example, Gibbs free energy of formation of thenitride compounds normalized by the number of nitride atoms in eachcompound formula) of the reactive metal-, ceramic- and braze-nitridecompounds exist in rank order. In an example where nitride compounds arerank-ordered, ΔG_(r),n of the reactive metal nitride (e.g., Li₃N) isless negative (i.e., more positive) than the ΔG_(r),n of the ceramicnitride (e.g., AlN) which is less negative than the ΔG_(r),n of thebraze nitride (e.g., TiN). Rank-ordering the materials in this mannermay reduce or eliminate a driving force for the rank-ordered compoundsto degrade. In some cases, the braze material also comprises materialsthat show low mutual solubility in the reactive material (e.g., reactivemetal or molten salt) and/or do not react with the reactive material(e.g., do not form intermetallic compounds with the reactive metal).Such a selection of materials can ensure thermodynamic stability of thereactive material (e.g., reactive metal), ceramic, and braze material.Additional materials can in some cases be added based on suchrank-ordering. For example, a component (e.g., ceramic) can be replacedby two or more components with more suitable rank-orderingcharacteristics.

In an example, a ΔG_(r),n (normalized by mole of oxygen) rank-orderedmaterial set includes Y₂O₃ (most stable compound of material set), Nd₂O₃(intermediate stability compound of material set), and Li₂O (leaststable compound of material set). The seal comprises Nd₂O₃ insulatingceramic and an active braze material comprising yttrium, and seals avessel containing lithium metal/metal vapors.

Nickel-cobalt ferrous alloy, titanium (Ti), nickel (Ni), zirconium (Zr)and 430 stainless steel (430 SS) can be stable in the presence of moltenlithium (Li), as indicated, for example, by phase diagrams that showthat lithium and the metal components of nickel-cobalt ferrous alloy and430 SS (e.g., Fe, Ni, Cr, Co) do not form intermetallic compounds withLi and that their respective solubility into (or with) Li is relativelylow (e.g., less than about 1 mol-%). Titanium-alloy braze can bond toferrous alloys, such as, for example, nickel-cobalt ferrous alloy and/or430 SS. In some cases, AlN, titanium-alloys, and nickel-cobalt ferrousalloy/430 SS are all stable in the presence of air at elevatedtemperatures. Thus, in an example, the method for choosing sealmaterials described herein shows that a seal comprising an insulatingceramic that comprises AlN, a braze that comprises Ti-alloy, and asleeve or collar that comprises one or more of a nickel-cobalt ferrousalloy, 430 SS and zirconium forms a suitable seal material set. Anotherexample of a suitable seal material set based on the process describedherein includes an Nd₂O₃ ceramic, a braze and/or pre-metallizationlayer(s) comprising yttrium and nickel, and a sleeve or collar thatcomprises one or more of a nickel-cobalt ferrous alloy and 430 SS.

FIG. 32 is an example of a method 3200 for selecting materials to form aseal for a high-temperature device. The device can comprise a reactivematerial. The method can comprise a rank-ordered free energy offormation selection process. Such a selection process can provide a pathtoward a seal that has long-term stability. Such a seal can comprisethermodynamically stable materials (e.g., stable ceramic, stable(active) braze material, braze that can reduce the ceramic). The methodcan include rank-ordering a set of materials based on increasing ordecreasing Gibbs free energy of formation (ΔG_(r)) of each of thematerials (3205). In some cases, the materials that are compared in theGibbs free energy comparison (i.e., the set of materials) comprisecompounds associated with one or more seal materials (e.g., compoundsassociated with the set of seal materials, e.g., compounds associatedwith a ceramic material and a braze material, such as, for example, anactive braze material) and/or compounds associated with the reactivematerial that is to be contained. The associated compounds may be rankedin accordance with their ΔG_(r) (e.g., Li₃N as the compound associatedwith the reactive material Li, TiN as the compound associated with theactive braze material Ti; or Li₂O as the compound associated with thereactive material Li, Y₂O₃ as the compound associated with the activebraze material). In some cases, the compounds comprise a common element(e.g., nitrogen in Li₃N, AlN and TiN, or oxygen in Li₂O, Nd₂O₃ andY₂O₃). In such cases, the rank-ordering can be based on increasing ordecreasing normalized Gibbs free energy of formation (ΔG_(r),n, whereΔG_(r),n is equal to ΔG_(r) divided by the stoichiometric number ofatoms of the common elements in the formula of the compound, such as,for example, ΔG_(r)=ΔG_(r,n)/1 for Li₃N and ΔG_(r)=ΔG_(r,n)/3 for Nd₂O₃where nitrogen and oxygen, respectively, is considered the commonelement) of each of the materials (e.g., the associated compounds). Thecommon element can be capable of forming a compound with the reactivematerial (e.g., Li₃N or Li₂O). The common element can be, for example,nitrogen, oxygen or sulfur (e.g., the compounds are nitrides, oxides orsulfides). As previously described, reaction(s) involving the commonelement may aid in bonding between the selected rank-ordered materials(e.g., AlN+Ti→TiN+Al, or Nd₂O₃+2Y→Y₂O₃+2Nd).

The method can further include selecting a subset of the rank-orderedmaterials (3210) (e.g., such that the selected materials remainrank-ordered). Next, in a step 3215, the method can include selecting aset of seal materials (e.g., a ceramic material and an active brazematerial) based on the selected rank-ordered materials. This mayeliminate a driving force for the selected rank-ordered materials todegrade when provided in the seal and/or exposed to the reactivematerial (e.g., Li). The selected set of seal materials can comprise aceramic material and an active braze material. Selecting the set of sealmaterials can comprise selecting one or more seal materials (e.g., firsta ceramic and then a braze) with associated compounds that have aΔG_(r),n that is more negative than a compound associated with thereactive material. The selection (e.g., a first step of the selection)may include selection of a ceramic material (e.g., AlN or Nd₂O₃,respectively) that is electrically insulating and that has a ΔG_(r),nthat is more negative than a compound associated with the reactivematerial (e.g., Li₃N or Li₂O, respectively). The selection (e.g., asecond step of the selection) may include selection of an active brazematerial (e.g., Ti-alloy or Y-alloy, respectively) with an associatedcompound (e.g., TiN or Y₂O₃, respectively) that has a ΔG_(r),n that isequal to or more negative than the ceramic material. In an example, thereactive material contained in the high-temperature device compriseslithium (Li). The selected rank-ordered materials in this example canbe, in order, lithium nitride (Li₃N), aluminum nitride (AlN) andtitanium nitride (TiN); the selected ceramic material can comprisealuminum nitride (AlN) and the selected active braze material cancomprise titanium (Ti). Alternatively, the selected rank-orderedmaterials in this example can be, in order, lithium oxide (Li₂O),neodymium oxide (Nd₂O₃) and yttrium oxide (Y₂O₃); the selected ceramicmaterial can comprise neodymium oxide (Nd₂O₃) and the selected activebraze material can comprise yttrium (Y). In some cases, the active brazematerial is also selected based on its stability with the reactive metal(e.g., a stable active braze material may have low (e.g., <1%, <0.1%)mutual solubility with the reactive material and/or the active brazematerial and the reactive material may be stable in the presence of eachother and/or not form intermetallic compounds). In some cases, theselected ceramic (AlN or Nd₂O₃, respectively) and active braze material(Ti or Y, respectively) are thermodynamically stable with Li. In someexamples, the seal may comprise a ceramic material that isthermodynamically stable in the presence of the reactive material, anactive braze material that is chemically stable with the reactivematerial, and where the active braze material chemically reacts with theceramic material (e.g., Ti+AlN→TiN+Al or Nd₂O₃+2Y→Y₂O₃+2Nd,respectively) and the compound product of that reaction (e.g., TiN orY₂O₃, respectively) is stable in the presence of the reactive material.

The method 3200 can further include selecting a sleeve or collar to jointo the seal (3220) and/or selecting a container of the device to join tothe sleeve or collar (3220). As described in greater detail elsewhereherein, the sleeve or collar can comprise a material that is chemicallycompatible with the seal and/or with one or more other materials of thedevice, and the container can comprise a material that is chemicallycompatible with the sleeve or collar and/or with one or more othermaterials of the device or seal. In some cases, one or more pairs of theselected rank-ordered materials can be CTE-matched. The steps of method3200 may be performed in a different order, or one or more steps may beomitted. Further, the method 3200 may in some cases include additionalor different step(s). One or more steps of method 3200 may be modifiedwithout altering its scope. For example, the method may be modified toaccount for presence of additional materials (e.g., a reactiveatmosphere or a reactive compound or element) during bonding (e.g.,allowing compounds with improved properties to be formed during bonding,such as, for example, by introducing an additional common element). Suchadditional materials may allow a modified set of rank-ordered materialsto be formed (e.g., including one or more compounds comprising theadditional material). A modified subset of rank-ordered materials (e.g.,including one or more compounds comprising the additional material)and/or a modified set of seal materials may then be selected.

The coefficient of thermal expansion (CTE) may be considered whendesigning a seal. The seal may comprise structural features that cancompensate for CTE mismatch. A CTE mismatch between various materialsmay not be a major concern during initial fabrication heat-up andbrazing process of the high temperature seal (e.g., since the componentsmay not be bonded, which allows for sliding interfaces). In someinstances, during cool-down (e.g., after the braze has melted, bondedand solidified), the materials can contract at different rates (e.g.,the insulator and metal sleeves can be exposed to large stresses).Therefore, one or more transition pieces may be added. The transitionpieces may have CTE values intermediate to that of the insulator and thecell top and/or can have spring-like design features (e.g., anickel-cobalt ferrous alloy, 430 SS or zirconium sleeve). In some cases,the transition pieces are thin relative to the insulator (e.g., thetransition piece can have a thickness that is less than about 50% or 10%the thickness of the insulator). In some cases, the braze material isseparated (e.g., kept away) from intended welding joints. In some cases,the seal includes a chemically stable material set (e.g., aluminumnitride ceramic, titanium-alloy braze, and nickel-cobalt ferrous alloyor 430 stainless steel sleeve), and can be CTE-matched or have a designthat can accommodate differences in CTE.

In some cases, the seal does not comprise materials that are exactlymatched in CTE and/or matched to the CTE of the housing and/orconductor. A mismatch in CTE can be compensated for by structuralfeatures and/or geometries such that the seal remains hermeticallysealed and/or forms a suitable electrical insulation (e.g., at theoperating temperature of the battery) and/or following one or morestart-ups of the battery (e.g., melting of the liquid metal electrodes).For example, the seal can have a shape (i.e., suitable geometry) suchthat the electrochemical cell is hermetically sealed (e.g., the geometryof the seal can comprise a ceramic material bonded to a flexible metalcomponent).

The CTE of the seal material may not be the same as the electricallyconductive housing and/or the conductor. The materials of the seal, theconductive housing and/or the conductor can have any amount of CTEmismatch. In some cases, the CTE of the seal or seal material (or aportion thereof) is greater than or equal to about 1%, 5%, 10%, 15%,20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%, 300%,400%, 500%, 600% or 700% different than the CTE of the electricallyconductive housing and/or the conductor. In some cases, the CTE of afirst seal material (e.g., metal collar) is less than about 1%, 5%, 10%,15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%,300%, 400%, 500%, 600% or 700% different than the CTE of a second sealmaterial (e.g., electrically isolating ceramic). In some cases, the CTEof a first seal material (e.g., metal collar) is at least about 1%, 5%,10%, 15%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%,300%, 400%, 500%, 600% or 700% different than the CTE of a second sealmaterial (e.g., electrically isolating ceramic).

The CTE of the seal can be mismatched (e.g., intentionally or purposelymismatched) to the CTE of the conductive housing and/or the conductor atthe operating temperature and/or during start-up of the cell (e.g.,starting from non-molten metal electrodes). In some cases, the CTE ofthe seal is at least about 10% different than the CTE of theelectrically conductive housing and/or the conductor at the temperatureat which the electrochemical cell is operated. In some instances, theCTE of the seal is at least about 1%, 5%, 10%, 15%, 20%, 25%, 30%, 40%,50%, 75%, 100%, 125%, 150% or 300% different than the CTE of theelectrically conductive housing and/or the conductor at any or alltemperatures between about −10° C. and the operating temperature (e.g.,at least about 200° C., 250° C., 300° C., 350° C., 400° C., 450° C. or500° C.).

In some cases, the geometry of the seal comprises a ceramic materialbonded to a flexible metal component. The flexible metal component canbe joined (e.g., welded or brazed) to the electrically conductivehousing and/or the conductor.

FIG. 10 shows examples of features that can compensate for a CTEmismatch. Examples include fins, cuts or bends in any configuration thatcan accommodate CTE mismatch (e.g., by spatial compliance). For example,a bend can be sinusoidal (either horizontally 1005 or vertically 1010),oval or tubular 1015, a sharp bend 1020, etc. The feature can beattached at a point above, below or in line with the top of the celland/or current collector. The feature can be joined to, part of, or cutaway from the cell housing and/or conductive feed-through. The featurecan be coated (e.g., to improve chemical stability to the internal orexternal environments of the cell). The orientation, thickness and/orshape can be optimized to increase stability and resistance to failurefrom vibration and mechanical forces.

Low CTE mismatch may be achieved through suitable material selection. Insome cases, one or more of the electrically conductive components of theseal comprise an electrically conductive ceramic (e.g., tungstencarbide) with a CTE that matches or is within less than or equal toabout 1%, 2%, 5%, 10% or 20% of the CTE of the electrically insulatingceramic. The electrically conductive (CTE-matched) ceramic can be joinedto both the insulating ceramic component and a metal collar. The joiningprocess may involve brazing, diffusion bonding, and/or welding. Theconductive ceramic may comprise, for example, tungsten carbide (WC),titanium carbide (TiC) and/or other carbides. The conductive ceramic maybe sintered with some fraction (e.g., between about 2% and 10%, or atleast about 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% in terms of weight,atomic, molar or volumetric composition) of metal (e.g., Co or Ni) whichcan allow for direct wetting of braze to the conductive ceramic.

In some cases, the electrically conductive components of the sealcomprise a metal with low CTE (e.g., less than about 1 ppm/T, 2 ppm/°C., 3 ppm/° C., 4 ppm/° C., 5 ppm/T, 6 ppm/° C., 7 ppm/° C., 8 ppm/° C.,9 ppm/° C., 10 ppm/° C., 11 ppm/° C., 12 ppm/° C. or 15 ppm/T), lowYoung's modulus (e.g., less than about 0.1 GPa, 0.5 GPa, 1 GPa, 10 GPa,50 GPa, 100 GPa, 150 GPa, 200 GPa or 500 GPa), high ductility (e.g., anultimate strength greater than about 100%, 200%, 300%, 400% or 500% thatof the yield strength), or any combination thereof. In some cases, theultimate strength can be greater than about 50%, 100% or 200% that ofthe yield strength of the material for it to have sufficient ductility.In some cases, the electrically conductive components do not comprise anelectrically conductive ceramic. Low CTE, low Young's modulus and/orhigh ductility component characteristics can lead to low stressconcentrations in the ceramic. Low Young's modulus componentcharacteristics can result in less stress generated between componentswith different CTE values (e.g., for a given CTE mismatch between twomaterials that are bonded together, if at least one material has a lowYoung's modulus, the strain generated by the CTE difference can causethe material with the low Young's modulus to “stretch,” resulting in arelatively small stress force between the two materials). Low CTE, lowYoung's modulus and/or high ductility component characteristics mayreduce likelihood of failure (e.g., due to reduced stress concentrationsand/or less stress generated). Metals that meet these specifications (inaddition to corrosion resistance to the internal and external cellenvironment) can include, for example, zirconium (Zr), high-zirconiumcontent alloys, tungsten (W), titanium (Ti), niobium (Nb), tantalum(Ta), nickel (Ni) and/or molybdenum (Mo).

In some implementations, the seal comprises a ceramic, one or more brazematerials and one or more metal collars. For example, two metal collarsmay be joined to the ceramic, one to each side of the ceramic. Each suchmetal collar may be further joined to additional metal collar(s). Thus,a compound metal collar may be created that comprises two or more metalcollars. In some examples, the compound metal collar comprises at leasttwo metal collars, of which at least one metal collar comprises amaterial that is suitably joined (e.g., using one type of braze) to theceramic and at least one metal collar comprises a material that issuitably joined to another component of the seal or of the cell (e.g.,using another type of braze). The two metal collars may also be joined(e.g., using yet another type of braze). In some instances, at least aportion (e.g., all) of the brazes used to join the metal collars of theseal to each other and/or to other parts of the cell may be of the sametype. In other instances, at least a portion or all of the brazes may beof different types. Further, one or more of the metal collars may bewelded rather than brazed, or welded and brazed. The seal may compriseone or more compound metal collars. In some examples, the seal comprisesat least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25,30, 40 or more individual metal collars. In an example, the sealcomprises 4 individual metal collars forming two compound metal collars.In some examples, at least a portion of the individual metal collars maycomprise the same material. For example, metal collars comprising thesame material may be used for joining metal collars to similar materials(e.g., similar cell housing or conductors materials).

In some cases, the seal comprises a ceramic, a braze material, a first(e.g., thin) metal collar, and/or a second metal collar. The first metalcollar may be brazed to the ceramic, and the second metal collar may bebrazed to the first metal collar. In some cases, the first metal collaris a low CTE material such as zirconium (Zr) or tungsten (W) and thesecond metal collar is a ferrous alloy, such as steel, stainless steelor 400 series stainless steel (e.g., 430 stainless steel). In someexamples, the first metal collar is less than about 10 micro-meters (μm,or microns) thick, 20 μm, 50 μm, 100 μm, 150 μm, 250 μm, 500 μm, 1,000μm, μm 1,500 or 2,000 μm thick.

In some cases, the seal comprises a ceramic, a braze, a first metalcollar, a second metal collar and a third metal collar. The first metalcollar may be joined to one part of the ceramic, and the second metalcollar may be joined to the first metal collar. The third metal collarmay be joined to a different part of the ceramic such that the firstmetal collar and the third metal collar are separated by anelectronically insulating ceramic material. Joints between the firstmetal collar and the ceramic and between the third metal collar and theceramic may both be hermetic. In some cases, the seal further comprisesa fourth metal collar that is joined to the third metal collar (e.g.,the first metal collar is joined to one part of the ceramic, the secondmetal collar is joined to the first metal collar, the third metal collaris joined to another part of the ceramic and the fourth metal collar isjoined to the third metal collar). The braze material used to join thefirst metal collar to the second metal collar may comprise or be similarto any of the braze compositions described herein. The first metalcollar or the second metal collar may be joined (e.g., using a brazecomposition similar to any of the braze compositions described herein,or welded) to the cell lid. The third metal collar may be joined to thefourth metal collar or directly to a negative current lead (e.g., brazedusing any of the braze compositions of the disclosure).

FIG. 23 is an example of a seal 2300 that comprises one ceramiccomponent (e.g., AlN) 2305. The ceramic component may be a washer. Theceramic component may be electrically insulating. The ceramic component2305 is joined with a first metal collar (e.g., Zr) 2310 via a firstmetal-to-ceramic joint (e.g., braze) 2315. The first metal collar 2310is joined with a second metal collar (e.g., 430 SS) 2320 via a firstmetal-to-metal joint (e.g., weld, braze) 2325. The second metal collar2320 is joined to a cell lid (e.g., 430 SS) 2330 via a secondmetal-to-metal joint (e.g., weld, braze) 2335. The seal furthercomprises a third metal collar (e.g., Zr) 2340 joined to the ceramiccomponent 2305 via a second metal-to-ceramic joint (e.g., braze) 2345.The third metal collar 2340 is joined with a conductor (e.g., negativecurrent lead) 2350 via a third metal-to-metal joint (e.g., weld, braze)2355. The seal 2300 may comprise one or more gaps (e.g., air gaps) 2360.

In some cases, the first, second, third, and/or the fourth metal collarcomprise structural features to relieve mismatches in the CTE of thejoined materials, described in greater detail elsewhere herein. Suchconfigurations may enable mechanically robust joining of the ceramic toone or more metal collars (e.g., the first metal collar, or the thirdmetal collar), and the joining of one or more metal collars (e.g., thesecond metal collar, or the third or fourth metal collar) to the celllid or a current conducting rod (also “conductor” herein) by simplewelding (e.g., TIG welding, or laser welding) or brazing.

A brazed ceramic seal may be used to hermetically and/or electricallyseal a system or vessel comprising a reactive material (e.g., anelectrochemical cell having liquid metals). FIG. 11 shows anelectrochemical cell having a brazed ceramic seal. A cell housing 1105can have an empty head space 1110, a molten negative electrode (e.g.,anode during discharge) 1115, a molten positive electrode (e.g., cathodeduring discharge) 1120 and a molten electrolyte 1125 disposedtherebetween. The liquid metal anode can be in contact with a conductivefeed-through 1130 that passes through the housing and serves as anegative terminal. The conductive feed-through can be electricallyisolated from the housing by the seal 1135. The liquid metal cathode canbe in contact with the housing, which can serve as a positive terminal.

In some cases, a brazed ceramic seal comprises a sub-assembly. Thesub-assembly can comprise the insulating ceramic bonded to one or more(e.g., two) flexible, spring-like or accordion-like components, referredto herein as metal sleeves. After the sub-assembly is fabricated, thesleeves can be brazed or welded to other cell components such as thecell lid and/or the negative current lead. Alternatively, all of thejoints can be created on the complete cap assembly by brazing (e.g., iftolerance limits are sufficiently tight). The chemical compatibilitybetween the braze materials and the atmospheres the materials will beexposed to, and the thermal robustness during high temperature operationand thermal cycling can be evaluated during design of the sub-assembly.In some instances, the ceramic material is aluminum nitride (AlN) orsilicon nitride (Si₃N₄), and the braze is a titanium alloy, titaniumdoped nickel alloy, a zirconium alloy or a zirconium doped nickel alloy.

FIG. 12 shows a schematic drawing of a brazed ceramic seal withmaterials that are thermodynamically stable with respect to internal1205 and/or external 1210 environments of a cell. Such materials may notrequire a coating. The various materials can have mismatched CTEs thatcan be accommodated for with one or more geometric or structuralfeatures 1215 (e.g., a flexible metal bend, fin, or fold). TheCTE-accommodating feature 1215 can be welded to a cell housing 1220(e.g., 400-series stainless steel) on one end and brazed 1225 to a firstmetalized surface 1230 of a ceramic material 1235 on the other end. Theceramic material 1235 can be, for example, aluminum nitride (AlN), boronnitride (BN) or yttrium oxide (Y₂O₃) as described herein. The ceramicmaterial can be brazed to a current collector (conductive feed-through)1240 by a braze 1245. The braze 1245 can comprise, for example, iron(Fe), nickel (Ni), titanium (Ti) or zirconium (Zr). The braze 1245 canbe in contact with a second metalized surface of the ceramic 1250 (e.g.,titanium or titanium nitride). Several layers of materials placedadjacent to each other can result in a CTE gradient that can mitigatemismatch.

FIG. 13 shows a seal where the ceramic and/or braze materials are notthermodynamically stable with respect to the internal 1205 and external1210 environments. In some instances, a coating can be applied to anoutside 1305 and/or an inside 1310 of the seal or enclosure components.

FIG. 14, FIG. 15, FIG. 16 and FIG. 17 show more examples of brazedceramic seals. In some cases, the seals extend above the housing by agreater distance. FIG. 14 shows an example of a seal on a cell which mayadvantageously not need a coating, not need a CTE mismatch accommodationfeature, and/or provide increased structural stability against vibrationand mechanical forces during operation, manufacturing or transportation.In this example, a housing 1405 can be sealed from a current collector1410. This arrangement can hermetically seal an inside 1415 of the cellfrom an outside 1420 of the cell. The components of the seal can bearranged vertically and can include a first braze 1425, a ceramic 1435,a first metalized surface 1430 of the ceramic, a second braze 1440, anda second metalized surface 1445 of the ceramic.

FIG. 15 shows a seal 1520 that can provide structural stability againstvibration and mechanical forces during operation, manufacturing andtransportation. In this example, CTE accommodating features 1505 aredisposed between a housing 1510 and a current collector 1515. The seal1520 can comprise a ceramic and two brazes in contact with metalizedsurfaces of the ceramic. In some cases, the seal is coated on an inside1525 and/or an outside 1530. In some cases, the coating(s) can compriseyttrium oxide (Y₂O₃).

FIG. 16 shows a seal 1610 with secondary mechanical load bearingcomponents 1605. The load bearing components are electrically insulatingin some cases. In some instances, the load bearing components do notform a hermetic seal. The seal 1610 (e.g., including a ceramic, twobrazes in contact with metalized surfaces of the ceramic, etc.) canhermetically seal a cell housing 1615 from a current collector 1620.

FIG. 17 shows an example of a secondary back-up seal 1705 (e.g., in caseof failure of a primary seal 1710). The secondary seal can fall ontoand/or bond over the primary seal in the case of failure of the primaryseal. In some cases, the secondary seal comprises glass that melts andbecomes flowable in the case of the primary seal failing. The meltedsecondary seal can pour down onto the failed primary seal and blockleaks. In some cases, the seal 1705 and/or the seal 1710 can beaxisymmetric (e.g., doughnut-shaped around a vertical axis through theaperture in the cell lid).

FIG. 18 shows another example of a seal configuration or sub-assembly(e.g., an alumina or zirconia seal with yttrium oxide (Y₂O₃) coating andiron- or titanium-based braze). The seal can include a collar 1805. Thecollar can provide mechanical support. The collar can comprise ferriticstainless steel welded to a rod. The seal configuration can include aconductor 1810. The conductor can be made of ferritic stainless steel(e.g., having a CTE of about 12). The conductor can be tolerant of oneor more reactive materials (e.g., tolerant of liquid lithium). Theconductor can be unlikely to change mechanical properties or form due toa phase transition. The conductor can have greater than or equal toabout 40% higher electrical conductivity than 304 stainless steel. Theseal can include a braze 1815. The braze can be disposed above and belowa ceramic washer 1820. The braze can be iron-based. The braze can have aCTE of about 12 and withstand high temperatures (e.g., 850° C. orgreater). The ceramic washer 1820 can be made of alumina (e.g., with aCTE of about 7), or zirconia (e.g., tetragonal with CTE of about 11).The low CTE mismatch of a zirconia washer can allow higher brazingtemperature without cracking. A cell housing 1825 can be made fromferritic steel and provide mechanical support through the ceramic (e.g.,the ceramic washer) to the collar. The seal configuration can comprise acoating (e.g., spray coating) 1830 (e.g., comprising yttrium oxide(Y₂O₃)). The coating can be provided on the cell housing (e.g., lid).The coating can be capable of being resistant to reactive materials(e.g., lithium (Li) vapor), inexpensive and/or mitigate ceramiccompatibility.

The length (e.g., horizontal extent) of the braze interface can be aboutthree to six times the thickness of the thinnest component being brazed.If the ratio of thickness to braze interface length is too low (e.g.,less than about three), the sealing area may be mechanically too weak tohold the brazed joint together. If the ratio is too high (e.g., greaterthan about six), the stresses on the sleeve due to CTE mismatch maycause the sleeve to fracture or pull away from the ceramic. In somecases, the braze interface absorbs the stresses induced by the mismatchof the CTEs of the sleeve, braze and ceramic induced by forming thejoint at high temperature and cooling down to room temperature afterfabrication.

FIG. 19 shows an example of a sub-assembly with braze length equal tobetween about 3 and 6 times the thickness of a metal sleeve. The metalsleeve (e.g., nickel-cobalt ferrous alloy, zirconium alloy) can have athickness of about 0.01 inches, 0.0080 inches, 0.0060 inches, 0.0030inches, 0.0015 inches or less. The sub-assembly can comprise a braze1905, one or more (e.g., nickel-cobalt ferrous alloy or stainless steel)sleeves (e.g., 1910 and 1915) and an insulator 1920.

FIG. 20 shows an example of a shape of a sub-assembly that canaccommodate CTE mismatch. The sub-assembly (i.e., seal) can comprise asleeve (e.g., a nickel-cobalt ferrous alloy sleeve) 2005 and aninsulator (e.g., a ceramic) 2010. Compressive forces can act in thedirection of indicated arrows 2015. Ceramic materials may be capable ofwithstanding a high level of compression. In some cases, seal designscan utilize this characteristic of ceramics to provide a reliable seal.In order to produce a compressive seal, outer material of the seal canhave a higher CTE value than inner material of the seal. Duringprocessing and fabrication, the sub-assembly can be heated, causing thematerials to expand. After reaching the braze melting temperature, thebraze joint can be formed, and upon cooling, the higher CTE material cancontract at a higher rate than the inner material to create acompressive seal. Due to the high temperature brazing operation andsubsequent cool-down, the sleeves (e.g., nickel-cobalt ferrous alloy orstainless steel sleeves) can apply a compressive force to the sealedbonding interface (e.g., nickel-cobalt ferrous alloy or stainlesssteel/insulator interface) due to the insulator in the centercontracting less. The example in FIG. 20 utilizes a Ti-alloy braze toform the sealing joint, and the compressive forces 2015 formed duringthe cool-down to press the sleeve 2005 (e.g., nickel-cobalt ferrousalloy sleeve) onto the insulator (e.g., ceramic) 2010, thus providing astable and robust seal. The seal in FIG. 20 is an example of acircumferential seal.

FIG. 21 is an example of a seal 2100 that comprises multiple ceramiccomponents. The ceramic components may be washers. The ceramiccomponents may be electrically insulating. The seal can electricallyisolate a conductor (e.g., negative current lead) 2120 from a cellhousing (e.g., cell lid) 2125 (e.g., by a hermetic seal). The seal inFIG. 21 is an example of a stacked seal design. In this seal design,three separate ceramic components (e.g., AlN) 2105 a, 2105 b and 2105 care positioned vertically on top one another. The ceramic components(e.g., insulators) are disposed between one or more metal sleeves orcollars 2110, 2115 and 2130 (e.g., zirconium metal, zirconium alloy, ornickel-cobalt ferrous alloy forming a flexible joint). In some cases,the collar 2130 may not be used and the collar 2115 may be joineddirectly to the cell housing 2125. The ceramic 2105 b may providesealing. The ceramic components 2105 a and 2105 c may provide stressand/or support for the seal. The ceramic components 2105 a and 2105 cmay or may not provide sealing. In some situations, the ceramiccomponents 2105 a and 2105 c may break (e.g., break and fall off). Insuch situations, the sealing provided by the central (in this casemiddle) ceramic component may not be affected.

The ceramic component 2105 b is joined with a first metal collar (e.g.,Zr) 2115 via a first metal-to-ceramic joint (e.g., braze) 2135. Thefirst metal collar 2115 may further be joined to the ceramic component2105 a via a fourth metal-to-ceramic joint 2170. In some cases, thefirst metal-to-ceramic joint 2135 and the fourth metal-to-ceramic joint2170 are the same type of joint (e.g., comprise the same brazematerial). The first metal collar 2115 is joined with a second metalcollar (e.g., 430 SS) 2130 via a first metal-to-metal joint (e.g., weld,braze) 2140. The second metal collar 2130 is joined to a cell lid (e.g.,430 SS) 2125 via a second metal-to-metal joint (e.g., weld, braze) 2145.The seal further comprises a third metal collar (e.g., Zr) 2110 joinedto the ceramic component 2105 b via a second metal-to-ceramic joint(e.g., braze) 2150. The third metal collar 2110 may further be joined tothe ceramic component 2105 c via a third metal-to-ceramic joint (e.g.,braze) 2165. In some cases, the second metal-to-ceramic joint (e.g.,braze) 2150 and the third metal-to-ceramic joint 2165 are the same typeof joint (e.g., comprise the same braze material). The third metalcollar 2110 is joined with a conductor (e.g., negative current lead)2120 via a third metal-to-metal joint (e.g., weld, braze) 2155. The seal2100 may comprise one or more gaps (e.g., air gaps) 2160.

In some cases, the sealing is provided by a central ceramic (e.g., themiddle ceramic 2105 b in FIG. 21) that is joined to metal collars (e.g.,metal collar 2110 and 2115 in FIG. 21) on opposite sides of parallelfaces of the ceramic (e.g., along interfaces/joints 2150 and 2135 inFIG. 21) in a stacked fashion. Two additional ceramic components (e.g.,the top ceramic 2105 a and the bottom ceramic 2105 c in FIG. 21) areincluded in the design and joined on the face of each metal collar thatis opposite to the face that is bonded to the central ceramic (e.g.,along brazing interfaces/joints 2170 and 2165 in FIG. 21). A stackedconfiguration with three ceramic components may create symmetric brazelengths on either side of the metal collars. Braze joints comprisingsymmetric braze lengths on either side of a metal collar may createsymmetric forces on the metal collar. This may enhance the overallstrength of the braze joint (e.g., by minimizing stress concentrationsand placing the metal under tension and the ceramic components undercompression). In some cases, a joint comprising a flat ceramic surfacethat is bonded to a flat metal surface is considered to be a face seal.

Different applications may benefit from different seal designs. Acircumferential (e.g., conical) seal design (e.g., see FIG. 20) mayprovide a robust seal design with a single ceramic component. The angledcircumferential surface on the ceramic may enable easier assembly (e.g.,the parts may fall into the proper configuration without the need forfixtures with tight tolerances or without the need for careful assemblyprior to brazing). The circumferential design may in some cases be ableto withstand greater CTE-mismatches between the metal collars and theceramic since the primary force exerted by the metal onto the ceramicafter cooling down from the brazing temperature may be a radiallysymmetric compressive force (e.g., due to ceramics generally beingstronger in compression than in tension). A stacked seal design (e.g.,see FIG. 21, or FIG. 23 which may be considered a special case of thestacked design with just one ceramic) may allow for lower costcomponents based on simpler machining of flat parallel surfaces on thetop and bottom of the ceramic instead of machining the outer diameterand/or machining the side of the ceramic to a specific conical angle(e.g., a conical angle of at least about 5, 10, 15, 20, 25, 30, 35, 40,50, or 75 degrees relative to a vertical orientation, or a conical angleof less than or equal to about 5, 10, 15, 20, 25, 30, 35, 40, 50, or 75degrees relative to a vertical orientation) as may be required by acircumferential seal. The stacked design may also enable designs withlower seal height (e.g., since the sealing interfaces are perpendicularto the height of the design). The seals of the disclosure (e.g., theseals in FIG. 20, FIG. 21 and FIG. 23) may be axially symmetric to aidin balancing forces on the seal. In some configurations, the stackedconfiguration may include 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18,20 or more ceramic components. The number of ceramic components may beconfigured to balance the forces in a given seal configuration. In somecases, the ceramic components may be symmetrically distributed on twosides of a central (e.g., middle) ceramic component. In some cases, theceramic components may be non-symmetrically distributed on two sides ofa central (e.g., middle) ceramic component. In some cases, the ceramiccomponents may be distributed in any configuration around (e.g., on twosides of, such as, for example, above and below) one or more ceramiccomponents that provide sealing. Further, thickness of the ceramiccomponents and/or of the metal collars may be selected to balance theforces in a given seal configuration. For example, metal collars joinedor bonded to the ceramic (e.g., the first metal collar or the thirdmetal collar) may have a first thickness, metal collars joined or bondedonly to other metal collars (e.g., in compound metal collars) may have asecond thickness, and metal collars joined or bonded to a conductor,cell housing lid and/or other part of the housing may have a thirdthickness (e.g., the third thickness may be equal to the first thicknessif the metal collar is also directly joined to the ceramic).

Brazing can be provided on either side of the sleeve or flexible joint(e.g., a balanced seal as shown in FIG. 21) or on just one side of thejoint (e.g., an unbalanced seal as shown in FIG. 23). Brazing on eitherside of each metal sleeve can balance the forces experienced by thesealing interfaces. An advantage of the balanced seal design may be thatthere can be limited force applied to the ceramic and minimal torquepresent during the cooling of the system. Such configurations can placethe sleeves (e.g., nickel-cobalt ferrous alloy sleeves) in tension andthe ceramics in compression. In an example, balancing of the seal mayenable stress (e.g., stress generated during a post-fabrication coolingprocess) to be less than the tensile strength of the ceramic. In anotherexample, balancing of the seal may enable strain (e.g., strain generatedduring a post-fabrication cooling process) to be less than the strainstrength (e.g., maximum strain that the ceramic can withstand prior tobreaking) of the ceramic. The ceramic may have a given strength. In someexamples, a strength value (e.g., tensile strength, ultimate strength,yield strength) of a ceramic material, such as, for example, AlN, BN,Al₂O₃, La₂O₃, Y₂O₃, MgO, SiC, TiC or Si₃N₄, can be greater than about 10mega-Pascals (MPa), 50 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa,350 MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa, 600 MPa, 650 MPa, 700 MPa,750 MPa, 800 MPa, 900 MPa, 1,000 MPa, 1,500 MPa, 2,000 MPa, 3,000 MPa,or 5,000 MPa.

FIG. 22 shows examples of forces on seals by providing images of resultsfrom computational models that predict stress and strain generatedduring a post-fabrication cooling process for a seal due to CTE mismatch(without incorporating plastic deformation). The models show the vonMises stress distribution (e.g., a calculated stress distribution basedon forces applied in three spatial dimensions that provides insight intothe likelihood of a stress-induced mechanical failure, e.g., if thecalculated von Mises stress exceeds the strength of the material, thematerial is predicted to fail) generated using a linear elastic modelfor a process involving joining ceramic and metal components together atcontacting interfaces at 850° C. and cooling the system to 25° C. In theexample image on the left in FIG. 22, the seal comprises only oneceramic insulator (e.g., as shown in FIG. 23). In the example image onthe right in FIG. 22, the seal comprises three ceramic insulators (e.g.,as shown in FIG. 21). As shown in these examples, the single ceramicseal on the left in FIG. 22 can be subject to larger von Mises stressesand/or strain than the three ceramic seal on the right in FIG. 22. Theshades in FIG. 22 represent different levels of the von Mises stress,with white being zero stress and black being the maximum stress on thescale, as indicated by an arrow in the direction of increasing stress2205.

While the sub-assembly is cooled, stresses may build up, leading toimmediate failure or failure when the seal is joined with the rest ofthe components of the cell top assembly. Since nickel-cobalt ferrousalloy can experience a phase transition at around 425° C. (e.g., asnoted by the sudden change in CTE as a function of temperature in FIG. 7and FIG. 8), it can maintain a higher stress level unless annealed belowthat temperature. In some cases, annealing of nickel-cobalt ferrousalloy is completed by a 30 minute soak at 850° C., which can ultimatelyyield high stresses in the sub-assembly. Higher temperature brazematerials may use 430 stainless steel sleeves, since they do notexperience grain growth after a phase transition leading to a change inshape or properties that may occur at prolonged periods of time at thedevice's (e.g., liquid metal battery's) operating temperature.

FIG. 24 shows an exploded view of a cell cap assembly having a cell top2405, a sub-assembly 2410 and a conductor 2415. The cell top can haveany suitable geometry (e.g., as long as it interfaces with the cell bodyand allows for features such as, for example, gas management (ifnecessary), and a hole for the sub-assembly to be welded to). Forexample, the cell top can comprise a first aperture for theconductor/sub-assembly and a second aperture for a gas managementconnection. Each aperture may be sealed with a seal of the disclosure.In some cases, the conductor has a low CTE (e.g., so that the part doesnot short or crack the ceramic or fail).

FIG. 25, FIG. 26 and FIG. 27 show examples of various features of seals.The seal in FIG. 25 utilizes corrosion resistant metals such asmolybdenum, tungsten, 630 SS or 430 SS 2505 (e.g., having a low CTE ofless than about 4 ppm/° C. or 10 ppm/° C.) and ceramics 2510 (e.g.,aluminum nitride (AlN)). The seal comprises a CTE-matching component2515 (e.g., at about 5.5 ppm/° C.) to allow for reduced or minimalstress build-up (e.g., between the metal 2505 and the ceramic 2510). TheCTE-matching component 2515 can comprise, for example, molybdenum, or analloy of tungsten and/or molybdenum. Examples of such materials areprovided in Example 1. The seal has a robust design for mechanicalloading and is resistant to electrical bridging shorts. The seal has alow profile design 2520 (e.g., about 0.25 inches), and can be welded orbrazed in a commercially scalable way 2525 (e.g., by laser or duringsub-assembly brazing).

In FIG. 26, parts of the seal are submerged into the cell such that theseal does not extend up beyond the surface of the cell lid. The seal caninclude a gas management port and nickel-cobalt ferrous alloy in placeof molybdenum. A flipped metal collar 2605 can reduce or eliminate thecatching of debris. In some cases, an inner diameter braze (e.g.,between nickel-cobalt ferrous alloy and aluminum nitride (AlN)) 2610 canresult in undesirable amounts of stress.

The cell shown in FIG. 27 can be sealed by a vacuum brazing process. Theseal can enter about ⅜ inch below the cell top, with about 0.05 inchextension above the cell top. The cell can have increased structuralcapability when compared to the cell in FIG. 26. The design can allowfor addition of a central pin after brazing, allowing for more controland flexibility during assembly. In some cases, the smaller gap betweenthe metal pieces can lead to a short by wetting of the ceramic 2705.

Seal ceramic component(s) (e.g., seal ceramic washers orisolators/insulators) may have a complex or compound shape. Such shapedceramic components may, for example, allow compressive forces on asealing ceramic (e.g., the middle ceramic 2105 b in FIG. 21 or theceramic component 2305) in a stacked configuration to improve sealingand durability (e.g., thereby enabling a hermetic seal that does notcrack during brazing or cell operation), facilitate easier assemblyand/or fixturing, and/or increase or physically block an electricalshorting path. Such seals may be configured for sealing a containercomprising a reactive material maintained at a temperature of at leastabout 200° C. (e.g., at least about 600° C. in some cases).

FIG. 39 shows cross-sectional views of a portion or component 3905 of aseal that comprises a simple ceramic component 3915 and a portion orcomponent 3910 of a seal that comprises a shaped ceramic component(e.g., L-shaped) 3920. The seal portions or components 3905 and 3910 canbe configured in stacked configurations (e.g., with one or more sealinginterfaces that are perpendicular to a direction parallel to a conductorthat passes through the seal). For example, the ceramic components 3915and 3920 can be center ceramic components that form a seal around aconductor (not shown).

FIG. 40 shows a cross-sectional view of an example of a seal 4000 with ashaped ceramic component 4005. The ceramic component 4005 may beelectrically isolating. The seal can electrically isolate a conductor(e.g., negative current lead) 4020 from a cell housing (e.g., cell lid).The ceramic component 4005 can be exposed to reactive material 4070within the cell housing. The ceramic component (e.g., AlN) 4005 may ormay not be surrounded by additional ceramic components (e.g., AlN). Forexample, the ceramic component 4005 can form a center ceramic componentof the seal 4000 (e.g., the ceramic component can be positioned in thecenter of a vertical stack of ceramic components). The ceramic component4005 can be surrounded by additional ceramic components (e.g., secondand third ceramic components 4010 and 4015 adjacent to the ceramiccomponent).

The ceramic component(s) (e.g., comprising aluminum nitride (AlN),silicon nitride (Si₃N₄) or magnesium oxide (MgO)) can be disposedbetween one or more metal sleeves or collars (e.g., zirconium metal,zirconium alloy, or nickel-cobalt ferrous alloy) forming a flexiblejoint. For example, a metal sleeve can be joined to the ceramiccomponent 4005, and the metal sleeve can be directly or indirectlyjoined to the container (not shown). An additional metal sleeve can bejoined to the conductor 4020. In some implementations, the metal sleevecan be joined to the container at a bottom surface of the ceramiccomponent and the additional metal sleeve can be joined to the conductorat a top surface of the ceramic component.

The first (e.g., center) ceramic component 4005 can be joined with afirst metal sleeve (e.g., Zr) 4030 via a first metal-to-ceramic joint(e.g., braze) 4040. The first metal sleeve 4030 may further be joined tothe second ceramic component 4010 via a second metal-to-ceramic joint4045. The first metal sleeve 4030 can be joined with a third metalsleeve (e.g., 430 SS) 4025 via a first metal-to-metal joint (e.g., weld,braze) 4060. In some cases, the third metal sleeve (e.g., cell topsleeve) 4025 may not be used and the sleeve 4030 may be joined directlyto the cell housing (not shown). A second metal sleeve (e.g., Zr) 4035can be joined to the first ceramic component 4005 via a thirdmetal-to-ceramic joint (e.g., braze) 4050. The second metal sleeve 4035may further be joined to the third ceramic component 4015 via a fourthmetal-to-ceramic joint (e.g., braze) 4055. The second metal sleeve 4035can be joined with the conductor 4020 via a second metal-to-metal joint(e.g., weld, braze) 4065. At least a subset of the metal-to-ceramicjoints 4040, 4045, 4050 and 4055 may be the same type of joint (e.g.,comprise the same braze material). At least a subset of themetal-to-metal joints 4060 and 4065 may be the same type of joint (e.g.,comprise the same weld or braze material).

In some implementations, the metal sleeve (e.g., the first metal sleeve4030) that is directly or indirectly joined with the container (e.g.,cell lid) may be joined with the ceramic component 4005 at thevertically lower sealing interface 4040, while the metal sleeve that isdirectly or indirectly joined with the conductor may be joined with theceramic component 4005 at the vertically higher sealing interface 4050.

The ceramic component 4005 can have a compound shape (e.g., L-shape).For example, the ceramic component 4005 can comprise a protrudingportion 4075 (shaded region) that substantially protrudes beyond asealing interface (e.g., beyond a sealing interface on the ceramiccomponent or beyond any combination of the sealing interfaces 4040,4045, 4050 and 4055). The protruding portion can have a thickness 4080that substantially exceeds a thickness of the sealing interface (e.g.,sealing interface 4040), thereby allowing the protruding portion tosubstantially protrude beyond the sealing interface (e.g., braze joint).The protruding portion can be adjacent to the conductor 4020. Theceramic component 4005 can increase or physically block an electricalshorting path between the conductor 4020 and the metal sleeve 4030. Asindicated in FIG. 40, the third metal sleeve 4025 may be at a positivepotential (“+ charge” and “+” signs to indicate positive polarity) withrespect to the conductor 4020 at a negative potential (“− charge” and“−” signs to indicate negative polarity). The second metal sleeve 4035may also be at a positive potential when joined with the cell lid viathe third metal sleeve 4025. The thickness 4080, which may be greaterfor a shaped ceramic component than for a simple ceramic component, mayaid in isolating the components with a positive polarity from thecomponents with a negative polarity. Additionally, the protrudingportion 4075 may protrude vertically downward from the seal in adirection parallel to the conductor. This downwardly protruding portionmay also aid in providing additional isolation or blockage between thecomponents with positive polarity and the conductor. Further, it mayallow fixturing (e.g., guided fixturing) of the seal and/or theconductor (e.g., when assembling the seal, or when fixturing the sealand/or the conductor in the container), as described in greater detailwith reference to FIG. 41.

FIG. 41 is another example of the seal in FIG. 40. In this example, aseal 4100 comprises a shaped first (e.g., center) ceramic component 4105joined with a first metal sleeve (e.g., Zr) 4130 via a firstmetal-to-ceramic joint (e.g., braze) 4140. The first metal sleeve 4130can further be joined to a second ceramic component 4110 via a secondmetal-to-ceramic joint 4145. The first metal sleeve 4130 can be joinedwith a third metal sleeve (e.g., 430 SS) 4125 via a first metal-to-metaljoint (e.g., weld, braze) 4160. The third metal sleeve (e.g., cell topsleeve) can be joined with the cell lid (e.g., 430 SS) (not shown). Asecond metal sleeve (e.g., Zr) 4135 can be joined to the first ceramiccomponent 4105 via a third metal-to-ceramic joint (e.g., braze) 4150.The second metal sleeve 4135 may further be joined to a third ceramiccomponent 4115 via a fourth metal-to-ceramic joint (e.g., braze) 4155.The second metal sleeve 4135 can be joined with a conductor 4120 via asecond metal-to-metal joint (e.g., weld, braze) 4165. Themetal-to-ceramic joints 4140, 4145, 4150 and 4155 may be face-sealing.The metal-to-metal joints 4160 and 4165 may be “diameter” braze jointsin some implementations. The metal sleeve 4135 may have a diameter of,for example, about 0.625 inches.

The metal sleeves can be joined to the first (e.g., center) ceramiccomponent and the second and third ceramic components via sealinginterfaces (e.g., metal-to-ceramic joints such as braze joints) withsubstantially the same (symmetric) sealing interface lengths (e.g.,braze lengths). The braze lengths may be, for example, less than orequal to about 0.040 inches, 0.050 inches, 0.060 inches, 0.070 inches,0.080 inches, 0.090 inches, 0.10 inches, 0.11 inches or 0.12 inches wide(e.g., from inner radius to outer radius), and less than or equal toabout 0.0005 inches, 0.001 inches, 0.015 inches, 0.020 inches, 0.025inches, 0.030 inches or 0.035 inches thick. For example, two or more(e.g., each) of the braze joints 4140, 4145, 4150 and 4155 can be about0.080 inches wide (e.g., from inner radius to outer radius) and about0.002 inches thick. The symmetric sealing interface lengths (e.g., brazelengths) may advantageously reduce asymmetric forces on the seal (e.g.,in a balanced configuration). For example, substantially the same (e.g.,identical) braze lengths for all braze joints may ensure that adjacentmaterials have substantially matching CTEs (e.g., closest CTE matchbetween adjacent materials), thus reducing potential for cracks formingwithin the ceramic upon brazing or cell operation.

The first ceramic component 4105 can comprise at least two portions thatare neither parallel nor perpendicular to each other when viewed in anaxially symmetric cross-section (e.g., a cross-section through thecenter of the conductor in a direction parallel to the conductor). Forexample, the first ceramic component can comprise an inner diameterchamfer 4185. Further, the compound shape can comprise a protrudingportion 4175 that substantially protrudes beyond a sealing interface(e.g., beyond a sealing interface on the ceramic component or beyond anycombination of the sealing interfaces 4140, 4145, 4150 and 4155). Theprotruding portion can have a thickness 4180 and can substantiallyprotrude beyond the sealing interface (e.g., braze joint) toward theconductor 4120. The inner diameter chamfer can extend along greater thanor equal to about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of thethickness 4180. The inner diameter chamfer may be determined by thesymmetric sealing interface length. For example, the chamfer may extendalong the entire thickness of the protruding portion 4175 in order tomatch the sealing interface lengths of sealing interfaces withoutprotruding portions. The chamfer may have an angle of greater than orequal to about 5°, 10°, 25°, 45°, 60°, 75° or 80°. Thus, the innerdiameter chamfer may allow symmetric sealing interface lengths to beachieved when combining simple and shaped ceramic components within theseal. The protruding portion 4175 may protrude vertically downward fromthe seal (e.g., from the bottom of the entire seal to allow outerdiameter fixturing) in a direction parallel to the conductor (e.g.,parallel with the length of the conductor in a vertical direction). Inthis example, this downwardly protruding portion is longer than in theexample of FIG. 40, thereby providing additional aid in fixturing (e.g.,guided fixturing) of the seal and/or the conductor. The length of thedownwardly protruding portion (e.g., of the L-shape) may allow, forexample, the outer diameter fixture of the seal to hold the firstceramic in place. In some cases, external fixturing may be used to alignat least a portion of components (e.g., in order to align all componentsof the seal/container/conductor assembly). Further, the conductor 4120may comprise one or more shoulders 4190 that protrude from the diameterof the conductor and allow the second metal sleeve 4135 to self-fixture.

FIG. 35 is a cross-section of a seal 3500 with a concentric accordionjoint. The seal 3500 is another example of a stacked configuration(e.g., a balanced configuration), and may, for example, increaseflexibility (e.g., the cell may be configured to flex like a spring toabsorb at least a portion of internal stresses caused by materialsexpanding/contracting upon heating/cooling without losing hermeticity),improve ease of manufacturing/assembly (e.g., supply chain, fabricationtechniques and assembly) and/or improve operational durability (e.g.,chemical corrosion resistance, electrochemical corrosion resistance andthermal stress management). Further, the seal may comprise seal ceramiccomponent(s) of a complex shape. The ceramic component(s) may be exposedto reactive material 3570 within the cell housing. The seal may beconfigured for sealing (e.g., hermetically) a container maintained at atemperature of at least about 200° C. (e.g., at least about 600° C. insome cases).

The seal may comprise one or more (e.g., 1 or 3) ceramic components(e.g., aluminum nitride (AlN), silicon nitride (Si₃N₄) or magnesiumoxide (MgO) washers). In configurations with multiple ceramiccomponents, additional ceramic components may be distributed (e.g., in avertically symmetric configuration) around a first (e.g., center)ceramic component. At least two metal sleeves (e.g., zirconium orstainless steel sleeves) may be joined to the ceramic component. Themetal sleeves may be flexible (e.g., bendable) to, for example, allowthe seal to absorb at least a portion of internal thermal stresses inthe seal.

The seal may comprise one or more face-sealing interfaces (e.g., brazejoints) that are substantially perpendicular to a direction parallel toa conductor that passes through the seal. In some implementations, allinterfaces, including metal-to-ceramic joints as well as metal-to-metaljoints, may be face-sealing. This may allow braze foils to be utilizedto join the seal and/or a reduced set of manufacturing steps (e.g., asingle furnace run) to be performed. The face-sealing interfaces (e.g.,braze joints) may be, for example, less than or equal to about 0.040inches, 0.050 inches, 0.060 inches, 0.070 inches, 0.080 inches, 0.090inches, 0.10 inches, 0.11 inches or 0.12 inches wide (e.g., from innerradius to outer radius). The face-sealing interfaces may be configuredto reduce or minimize stress.

With continued reference to the example in FIG. 35, the seal 3500comprises a first (e.g., center) ceramic component (e.g., AlN) 3505joined to a first metal sleeve (e.g., Zr) 3510 and a second metal sleeve(e.g., Zr) 3515. In some implementations, the metal sleeves 3510 and3515 may be substantially similar (e.g., identical). This may allowfewer unique parts to be manufactured per seal (e.g., the number ofdifferent diameters of rod stock and fabrication steps may be reduced).The seal further comprises a first coupler (e.g., 430 SS cell topcoupler) 3520 between a container (e.g., cell top) 3525 and the firstmetal sleeve 3510. The first coupler 3520 may be flexible, therebyallowing the seal to absorb at least a portion of internal thermalstresses. The metal sleeves 3510 and 3515 and the first coupler 3520 maybe shaped to create a spring to absorb stresses (e.g., internalstresses) related to thermal expansion, thus decreasing the amount ofstress transferred to the ceramic components (e.g., insulators) of theseal. The seal further comprises a second coupler (e.g., 430 SS negativecurrent lead (NCL) coupler) 3530 between a conductor (e.g., 430 SSnegative current lead) 3535 and the second metal sleeve 3515. The firstcoupler 3520 and the second coupler 3530 may be joined with the firstmetal sleeve 3510 and the second metal sleeve 3515, respectively, viasealing interfaces (e.g., face-sealing braze joints) 3540.

The first metal sleeve 3510, the second metal sleeve 3515, the firstcoupler 3520 and/or the second coupler may be configured with a bend(e.g., at least about 10°, 20°, 30°, 45°, 60°, 75° or 80° slope) 3545 toallow for self-fixturing of the seal during assembly at room temperatureand/or when the (e.g., entire) seal is at its brazing temperature. In anexample, a bend of at least about 30° is used. Thus, the couplers mayself-fixture with their respective metal sleeves. Gaps between thesecomponents may be configured to take into account each material's CTEsuch that interference is limited or eliminated upon heating up.Further, the first metal sleeve 3510, the second metal sleeve 3515and/or the first coupler 3520 may comprise angled self-fixturingfeatures. For example, the first metal sleeve 3510 and the first coupler3520 may comprise complementary kinks or hooks 3560. Such self-fixturingfeatures may allow parts to, for example, slide into position (e.g.,align) during assembly. Similarly, the conductor 3535 may self-fixturewith the second coupler 3530 (e.g., via mating connection 3565).Providing the conductor and the second coupler separately may in somecases reduce waste upon fabrication. The conductor may nest with secondcoupler and/or one or more other components of the seal. The metalsleeves 3510 and 3520 and/or the first coupler 3520 may be configured tolimit waste upon fabrication (e.g., inner diameter and outer diameterchoice of parts may allow more appropriate standard dimensions offeedstock to be used), allow easier (e.g., less time-consuming) and/orallow greater flexibility during fabrication (e.g., capability to usemultiple different machining alternatives, such as, for example, lathe,CNC or stamping). The metal sleeves 3510 and 3520 may have a diameterof, for example, about 0.990 inches and a thickness of, for example,about 0.015 inches. In some cases, a single fixture, along withself-fixturing may be used to align all components of the seal and/or ofthe seal/container/conductor assembly.

In some implementations, the seal may further comprise additionalceramic components (e.g., AlN balancing ceramics). In this example, theseal comprises two additional ceramic components 3550 and 3555 joinedwith the first metal sleeve 3510 and the second metal sleeve 3515,respectively. One or more of the ceramic components may be chamfered.For example, only the first ceramic component, at least a portion of theceramic components or all of the ceramic components may be chamfered.Different ceramic components may comprise substantially similarchamfers. Alternatively, different ceramic components may comprisedifferent chamfers. The chamfer(s) may have an angle of greater than orequal to about 5°, 10°, 25°, 45°, 60°, 75° or 80°. The chamfers may aidin fixturing of seal components. Each ceramic component may have a givenheight (or width or another characteristic dimension). For example, thefirst ceramic component (e.g., corresponding to a shorting length) mayhave a height of less than or equal to about 0.200 inches, while thesecond and third ceramic components may have a height of less than orequal to about 100%, 80%, 60%, 40% or 20% of the height of the firstceramic. Stress modeling optimization may be used in some cases to guideor determine suitable thickness of materials.

At least a portion (e.g., all) of the face-sealing interfaces (e.g., thesealing interfaces between the ceramic components 3505, 3550 and 3555and the metal collars 3510 and 3515, and the sealing interfaces 3540)can comprise, for example, about 0.060 inches wide (e.g., from innerradius to outer radius) braze joints. At least one of the face-sealinginterfaces may be configured as a concentric accordion joint (e.g.,concentric accordion in, such as, for example, in an axisymmetric sealas shown FIG. 36). A concentric accordion joint may comprise the firstcoupler 3520, the first metal sleeve 3510 and a sealing interface 3575.The concentric accordion joint may further comprise the first ceramiccomponent 3505 and, in some cases, the second ceramic component 3550and/or the sealing interface 3580. Another concentric accordion jointmay be at least partially formed by the second coupler 3530, the secondmetal sleeve 3515 and a sealing interface 3585. This (e.g., partial)accordion joint may further comprise the first ceramic component 3505and, in some cases, the third ceramic component 3555 and/or the sealinginterface 3590. In some implementations, the concentric accordion jointmay be used in non-axisymmetric seals (e.g., seals that are square oroval rather than circular).

FIG. 36 is a cut-away view of another example of a seal 3600 with aconcentric accordion joint. The seal 3600 comprises a first (e.g.,center) ceramic component (e.g., AlN) 3605 joined to a first metalsleeve (e.g., Zr) 3610 and a second metal sleeve (e.g., Zr) 3615, afirst coupler (e.g., 430 SS cell top coupler) 3620 between a container(e.g., cell top) (not shown) and the first metal sleeve 3610, a secondcoupler (e.g., 430 SS negative current lead (NCL) coupler) 3630 betweena conductor (e.g., 430 SS negative current lead) 3635 and the secondmetal sleeve 3615. The first coupler 3620 and the second coupler 3630may be joined with the first metal sleeve 3610 and the second metalsleeve 3615, respectively, via sealing interfaces (e.g., face-sealingbraze joints) 3640. The seal further comprises two additional ceramiccomponents 3650 and 3655 joined with the first metal sleeve 3610 and thesecond metal sleeve 3615, respectively. The seal 3600 may be axiallysymmetric (as shown) and may be exposed to reactive material 3670 withincontainer. In some cases, the conductor 3635 may comprise a hole 3680(e.g., a threaded hole used to connect to a busbar/interconnect or anadjacent cell).

Compound Seals

Seals of the disclosure may include compound seals (e.g., double seal)and compound seal cell cap assemblies (e.g., double seal cell capassembly). Compound seals may seal a high temperature container from anenvironment external to the container. Such seals may be configured forsealing a container comprising a reactive material maintained at atemperature of at least about 200° C. (e.g., at least about 600° C. insome cases). The seals may be exposed to an internal atmosphere of thecontainer as well as an external atmosphere outside the container. Theexposure internal and external atmospheres may place different materialsrequirements on the compound seal. While single seals may be configuredto contain (e.g., hermetically) the internal materials of a cell,battery or other high-temperature device while resisting corrosion fromthe surrounding environments (e.g., inside and outside environments), acompound seal may divide the environments and address the sealing indifferent environments individually. For example, a double seal may becapable of withstanding two different environments. The double seal maycomprise two seals joined together in such a manner that results in thedouble seal effectively resisting corrosion from both environments.

A compound seal may be advantageously used, for example, in situationswhere a set of stability (e.g., due to exposure), durability, lifetime,flexibility, space (e.g., nested seals), strength and/or otherrequirements are difficult to meet by a single set of materials. Forexample, a double seal may comprise a first seal that is stable when incontact with the reactive material (also “active stable seal” herein)and a second seal that is stable when in contact with the externalenvironment such as, for example, air or any other type of surroundingatmosphere (collectively referred to as “air stable seal” herein). Thereactive material may comprise, for example, a reactive metal or a vaporof a reactive metal, a molten salt or a vapor of a molten salt, or acombination thereof. The reactive metal may be molten or liquid. Forexample, the first seal may resist or withstand corrosion (e.g.,electrochemical and chemical corrosion) by molten lithium and/or amolten lithium salt (e.g., LiCl, LiF or LiBr), and the second seal may(e.g., substantially) resist or withstand oxidation by air. For example,the second seal may resist oxidation by air resulting in an increase ina leakage rate (e.g., gas leakage rate) of the second seal (e.g., afteran initial oxidation process resulting in a passivating and stable oxidelayer, the second seal may resist further oxidation by air). The firstseal may comprise a solid material that is not stable when in contactwith the external environment, the second seal may comprise a solidmaterial that is not stable when in contact with the reactive material,or a combination thereof. Alternatively, at least one of the seals maybe of multiple types. For example, an air stable seal may in some casesbe an active stable seal, and vice versa.

A given seal configuration may be used as an active stable seal and/oran air stable seal. In some cases, a seal configuration may be adaptedfor use as a given type of seal. For example, materials selection orsizing may be adapted to enable use of a given seal configuration as anactive stable seal or an air stable seal. Examples of active stableseals include, for example, the seals in FIG. 35, FIG. 36, FIG. 39, FIG.40 and FIG. 41. For example, the shaped ceramic seals of FIG. 39, FIG.40 and FIG. 41 may be stable when in contact with the reactive material.A cell cap assembly of a cell or container that comprises the shapedseal ceramic may further comprise an additional seal that is stable whenin contact with the external environment and within which the shapedseal is nested. Another example includes the concentric accordion jointseal of FIG. 35 and FIG. 36. In some examples, this seal may be stablewhen in contact with the reactive material but not when in contact withthe external environment.

The seals of a compound seal may be synergistically combined. Forexample, if the current lead 4020 (e.g., the top of the protrudingcurrent lead 4020) of the seal 4000 in FIG. 40 is physically attached orsecured to the metal sleeve 4025 or 4030 or a cell lid (e.g., by one ormore additional components not shown in FIG. 40, such as, for example,via an additional (e.g., air stable) seal used in combination (e.g., ina double seal configuration) with the (e.g., active stable) seal 4000),the metal sleeves 4030 and 4035 configured in accordance with FIG. 40may put the ceramic component (e.g., center ceramic component) 4005 incompression (e.g., rather than in tension which may lead to expandedspaces within the seal as the center ceramic component is squeezed) asthe seal is heated or cooled such that the ceramic component iscompressed upon thermal expansion of the conductor, the container,and/or the additional seal. Such thermal expansion may be of importancein some implementations where, as the seal components are cooled afterforming the seal (e.g., by brazing), they may contract at differentrates due to different CTEs (e.g., with ceramics contracting the leastand stainless steel parts, such as, for example, the conductor and/orthe container, contracting the most) and the thermal expansion mayeffectively pull at the braze joints and ceramics of the seal, thusleading to mechanical failure in some cases. The switched locations ofthe metal sleeves 4030 and 4035 (e.g., with respect to the configurationin FIG. 21) may in some cases (e.g., for an AlN ceramic in a balancedceramic seal configuration) flip the internal stresses of the ceramiccomponent 4005 from being in tension to in compression.

A compound seal may comprise, for example, greater than or equal to 2,3, 4, 5, 6, 7, 8, 9, 10, 12, 14 or more seals. When the number of sealsis equal to or exceeds 2, individual seals may in some cases be exposedto atmospheres intermediate (e.g., mixtures) or altogether different(e.g., inert) from at least one of the internal and external atmospherespreviously described. At least a portion (e.g., greater than or equal toabout 1/10, ⅕, ¼, ⅓, ½ or more) of the seals in a compound seal may behermetic. For example, the first and second seals in a double seal mayeach be hermetic.

FIG. 33 is a cross-sectional view of an example of a double seal 3300.The double seal 3300 comprises a first seal (e.g., active stable seal)3305 and a second seal (e.g., air stable seal) 3310. The first seal andthe second seal may each provide a seal (e.g., electrically isolatingseal) between a container (e.g., cell top) 3315 and a conductor (or athermocouple or voltage sensor) 3320 that protrudes through thecontainer through an aperture in the container. The first seal 3305 maybe exposed to an atmosphere 3325 comprising, for example, active (e.g.,reactive) cell materials (e.g., Li, LiF, LiCl or LiBr as shown). Thefirst seal 3305 may be stable when in contact with the atmosphere 3325.The second seal 3310 may be exposed to an atmosphere 3330 comprising,for example air (e.g., O₂ as shown, with O₂ illustratively bouncing offof the seal). The second seal 3310 may be stable when in contact withthe atmosphere 3330. The seal 3300 may comprise a pocket 3365 betweenthe first and second seals.

Compound seals may comprise one or more seals arranged in acircumferential configuration, one or more seals arranged in a stackedconfiguration, or a combination thereof. In this example, the secondseal is arranged in a circumferential configuration and the first sealis arranged in a stacked configuration. In a double seal, for example,the first and second seals may each be of any suitable configuration. Inthis example, the configuration of the first seal may be similar to theseal of FIG. 21 and the configuration of the second seal may be similarto the seal of FIG. 20. The first seal and the second seal may eachcomprise one or more insulators (e.g., ceramic components) and one ormore collar or sleeves (e.g., metal collar or sleeves) adjacent to theinsulator (e.g., ceramic component). For example, the first sealsubassembly can comprise insulators (e.g., ceramics) 3350 and sleeves(e.g., metal) 3355, and the second seal sub-assembly can comprise aninsulator (e.g., a ceramic) 3345 and sleeves (e.g., metal) 3340. Thefirst seal may comprise an additional sleeve (e.g., metal) 3360 thatjoins the seal, via one of the sleeves 3355, with the cell top 3315. Thesecond seal may be joined with the cell top 3315 via a bushing (e.g., anaxisymmetric bushing) 3335 joined with one of the sleeves 3340. Thefirst and second seals may each be joined with the conductor 3320 viaone of the sleeves 3355 and 3340, respectively.

FIG. 34 is another example of a double seal 3400 comprising a first seal(e.g., active stable seal) 3405 and a second seal (e.g., air stableseal) 3410. In this example, the configuration of the first seal may besimilar to the seal of FIG. 40 and the configuration of the second sealmay be similar to or modified the seal of FIG. 20. The first sealsubassembly can comprise insulators (e.g., 3 ceramic componentsincluding a shaped center ceramic component) 3450 and sleeves (e.g.,metal) 3455, and the second seal sub-assembly can comprise an insulator(e.g., a ceramic) 3445 and sleeves (e.g., metal) 3440. The double sealmay comprise a bushing 3435. In this example, the first and second sealsare first joined with the bushing, and the bushing is joined with acontainer (e.g., cell top) 3415. The first seal may comprise anadditional sleeve (e.g., metal) 3460 that joins the seal, via one of thesleeves 3455, with the bushing 3435. The second seal may be joined withthe bushing 3435 via one of the sleeves 3340 (e.g., adapted to seal withthe bushing at a horizontal sealing interface 3470 rather than avertical sealing interface as is FIG. 33). The first and second sealsmay each be joined with a conductor 3420 via one of the sleeves 3455 and3440, respectively.

The first seal 3405 may be exposed to an atmosphere 3425 comprising, forexample, active (e.g., reactive) cell materials. Sealing of the firstseal to the container 3415 may be performed in an environment comprisinga first inert gas (e.g., He—Ar or He-inert gas mixture). Thus, theatmosphere 3425 may comprise the active cell materials mixed with inertgas and substantially no air or other external atmosphere 3430. Thesecond seal 3310 may be exposed to an atmosphere 3430 comprising, forexample, air. The seal 3400 may comprise a pocket 3465 between the firstand second seals. The pocket may be filled, as indicated by arrows 3475and 3480, with a second inert gas (e.g., He—Ar or He-inert gas mixture)via one or more ports 3485 and 3490, respectively, that allow the secondinert gas to enter the pocket. The port 3475 may be provided, forexample, in the bushing 3435 or in the conductor (also “negative currentlead (NCL)” herein) 3420. The ports 3485 and 3490 may be used asalternatives or in concert. For example, the pocket may be filled eitherthrough the port 3490 comprising a hole through the conductor, orthrough the port 3485 comprising a hole through the bushing between thefirst seal and the second seal. In the example of FIG. 33, a port may beprovided as a hole through the conductor 3320 or as a hole in thebushing 3335 between the second seal and the container 3315. The hole(s)in the conductor/bushing may provide process flexibility when joiningthe double seal (e.g., when manufacturing and assembling the first andsecond seals and joining them with the container).

Sealing a high temperature device, container or electrochemical cellcomprising a container (e.g., container 3415) with a double seal (e.g.,seal 3400) may include sealing a first seal (e.g., first seal 3405) inan environment comprising the first inert gas to capture the first inertgas inside the container. A second seal (e.g., second seal 3410) maythen be sealed and may form a pocket (e.g., pocket 3465) between thefirst seal and the second seal. The first and/or second seals (e.g.,each previously formed by laser-welding in an environment comprising anon-inert gas such as, for example, air) may be sealed to the containerand a conductor (e.g., conductor 3320), by, for example, TIG-welding. Aspreviously described, the first and second seals may in some cases beindirectly sealed to the container via, for example, a bushing (e.g.,bushing 3335 or 3435). The first seal may be sealed to thecontainer/conductor, followed by sealing the second seal to thecontainer/conductor. Alternatively, the first and second seals may bothbe joined to the conductor and then sealed to the container (e.g., viathe bushing), or the first and second seals may both be joined with thebushing/conductor and the bushing can then be sealed to the container. Acap assembly may comprise the container (e.g., cell lid) and the firstseal, or the container, the first seal and the second seal.

The pocket may be filled with a second inert gas via a port (e.g., port3485 and/or 3490) and then sealed (e.g., by closing the port via aweld), thus sealing the pocket and capturing the second inert gas in thepocket. The first and second inert gases may or may not be the same(e.g., may or may not have the same composition). For example, the firstand/or second inert gas can comprise helium (He), argon (Ar), a mixtureof He and Ar, a mixture of He and another inert gas (e.g., neon, kryptonor xenon), a neat or mixed inert gas other than He and Ar, or anycombination thereof. An inert gas may or may not be a noble gas and mayin some cases include any gas that is stable in a given environment(e.g., stable with reactive material inside the container at celloperating temperature). The first and/or second inert gas may comprise,for example, between about 1% and 5%, 1% and 10%, 1% and 15%, 1% and 25%or 1% and 50% He with balance Ar. In an example, the first and secondinert gases suitable for a liquid metal battery cell comprising lithiumeach comprise between about 1% and 15% He with remainder Ar.

FIG. 37 is a cross-sectional view of an example of an air stable seal3700. The air stable seal 3700 comprises an insulator (e.g., a ceramiccomponent) 3705 and at least two (e.g., metal) sleeves 3710 and 3715joined to the ceramic component. In some cases, a CTE of at least one ofthe metal sleeves substantially matches a CTE of the ceramic component.For example, the ceramic component 3705 may comprise alumina and themetal sleeves 3710 may comprise an alloy comprising greater than orequal to about 42% Ni and greater than or equal to about 58% Fe, suchas, for example, alloy 42. This may reduce internal stresses within theceramic component (e.g., alloy 42 may be used for both sleeves, and itsCTE may closely match the CTE of alumina, allowing low internal stresseswithin the alumina ceramic). The first metal sleeve (also “NCL sleeve”herein) 3710 may be joined with a conductor or NCL 3720. The secondmetal sleeve (also “cell top sleeve” herein) 3715 may be joined with acontainer (e.g., cell top) 3725. In some cases, the cell top sleeve mayrelieve stress (e.g., upon reheat). The seal 3700 may be stable when incontact with an external environment (e.g., air) 3730. The seal 3700 mayalso be exposed to and be stable when in contact with an environment(e.g., an inert gas, or a mixture of the environment 3730 and an inertgas) 3735. The seal 3700 may not be exposed to a reactive material orenvironment within the container (not shown). For example, the ceramiccomponent 3705 may not be exposed to the reactive material. The seal3700 may not be stable when in contact with the reactive material orenvironment within the container. In some cases, the seal 3700 may bestable when in contact with a mixture of the environment within thecontainer and an inert gas. The seal 3700 may be hermetic (e.g., whenmaintained at a temperature of at least about 600° C.).

The seal 3700 may be suitable for use in a compound seal (e.g., in thedouble seals of FIG. 33 and FIG. 34 instead of the seals 3310 and 3410).For example, a high temperature device, container or electrochemicalcell comprising the seal 3700 can also comprise an additional sealnested within the seal 3700 (see examples of nested seals in FIG. 33 andFIG. 34). The additional seal (e.g., active stable seal) may be stablewhen in contact with the reactive material within the container.

The seal 3700 may be configured to bear an increased amount of verticalload (e.g., to allow increased vertical weight). For example, the sealmay be configured of bearing a vertical load of at least about 2 Newtons(N), 4 N, 6 N, 8 N, 10 N, 12 N, 14 N, 16 N, 18 N, 20 N, 25 N, 50 N, 75N, 100 N, 500 N, 1,000 N, 2,000 N, 5,000 N or more. In an example, theseal is configured to bear a vertical load of at least about 10 Newtons.The vertical load-bearing capability may allow at least a portion of theload (e.g., vertical load from other cells) to be transferred to thecontainer (e.g., as opposed to the additional seal).

The seal 3700 may be configured such that its height 3740 is small(e.g., smaller than in alternative seal configurations). A reducedheight may allow cells (e.g., battery cells within a system) to bepacked closer to one another (e.g., with a reduced spacing betweenvertically stacked electrochemical cells). In some cases, closer cellpacking may enable or improve self-heating of group(s) of cells (e.g.,facilitate implementation of a self-heating core). The height 3740(e.g., above a top plate 3745 of the container) may be less than about 5inches, 4 inches, 3 inches, 2 inches, 1 inch, 0.5 inch, 0.25 inch or0.125 inch. The seal may be configured such that its diameter 3755 islarge (e.g., smaller than in alternative seal configurations). Thelarger diameter may enable, for example, nesting of the additional(e.g., active stable) seal within this seal. The seal may have an outerdiameter of, for example, at least about 0.5 inch, 1 inch, 1.5 inch, 2inches, 2.5 inches, 3 inches or more. The conductor 3720 may protrudethrough the container through an aperture 3750 with a diameter of atleast about 0.5 inch, 1 inch, 1.5 inch or 2 inches. In an example, theseal has an outer diameter of at least about 1 inch or the aperture isat least about 0.5 inches in diameter.

The metal sleeve 3710 and/or 3715 may have a thickness of less than orequal to about 0.040 inches, 0.030 inches, 0.020 inches or 0.010 inches.In an example, the metal sleeve(s) have a thickness of about 0.020inches. The metal sleeve(s) may allow flexibility during fabrication(e.g., capability to use one or more fabrication methods such as lathe,CNC and stamping). The metal sleeve(s) may have an outer diameter ofless than or equal to about 3 inches, 2 inches, 1.5 inches, 1 inch, 0.5inch or less. In an example, the metal sleeve(s) have an outer diameterof 1.530 inches, which provides flexibility in manufacturingrequirements. The NCL sleeve may be configured such that its diameteris, for example, larger than in alternative seal configurations; itsshape may be configured to absorb stress as the seal heats up and growsdue to thermal expansion. The ceramic component 3705 may have acharacteristic dimension (e.g., height) of less than or equal to about0.100, 0.150, 0.200, 0.250 or 0.300 inches and a width of less than orequal to about 100%, 80%, 60%, 40% or 20% of the characteristicdimension.

A first of the at least two metal sleeves may be joined to the ceramiccomponent and the conductor via a braze joint with a braze length ofless than or equal to about 0.040 inches, 0.060 inches, 0.070 inches,0.080 inches or 0.100 inches (e.g., about 0.080 inches), therebyreducing thermal stresses at the braze joint. The cell top sleeve 3710may be configured to decrease or minimize stress at the braze joint(e.g., through a reduced braze length between the ceramic and themetal).

FIG. 38 is a sectioned side view of the seal in FIG. 37, showing thestructured shape of the seal. The seal may comprise a ceramic component3805 joined with a first metal sleeve 3810 and a second metal sleeve3815. The first metal sleeve may be joined with a conductor (not shown)and the second metal sleeve may be joined with a container or cell top(not shown).

In some implementations, seals, sub-assemblies, conductors and/orhousings may comprise structural features (e.g., mating features) or becombined with structural members such as, for example, flanges, hooks,ledges, interlock features, weldable tabs, brazable tabs, snap fits,screw fits, screws, nuts, bolts and/or other structural members tofacilitate a secure connection of the sealing arrangements herein. Insome cases, such mating features may be used in concert with welding,brazing, coating, metalized surfaces, structural features for CTEmismatch, etc. Further, seals, sub-assemblies, conductors and/orhousings may comprise structural features to facilitate interconnectionbetween cells and groups of cells. In some cases, such features may bedirected at reducing or minimizing stress and forces acting on seals asa result of interconnection. Further, the seals herein may be configuredfor use in concert with various interconnections features (e.g., currenttransfer plates). Configuration of the seals may in such cases include,for example, material considerations (e.g., material compatibility ofseals and interconnections), desired system resistance (e.g., affectingchoice of seal with a given resistance), space and operating conditionconsiderations (e.g., affecting choice of a seal that is compatible withspace constraints imposed by a given interconnection arrangement and/oroperating conditions), and so on.

Interconnections

Wired or wire-less (e.g., direct metal-to-metal) interconnections may beformed between individual electrochemical cells and/or between groups ofelectrochemical cells (e.g., modules, packs, cores, CEs, systems, or anyother group comprising one or more electrochemical cells). In somecases, groups of cells may be joined via one or more cell-to-cellinterconnections. In some cases, groups of cells may be joined via agroup-level interconnection. The group-level interconnection may furthercomprise one or more interconnections with one or more individual cellsof the group. The interconnections may be structural and/or electrical.Cells and/or groups of cells may be assembled (or stacked) horizontallyor vertically. Such assembled cells and/or groups of cells may bearranged in series or parallel configurations. Further, groups of cellsmay be supported by various frames. The frames may provide structuralsupport and/or participate or aid in forming the interconnections (e.g.,frames on groups of cells may mate or be connected).

An interconnect may refer to any electrical connection other than adirect metal-to-metal joint. Interconnects can include wires or bentsheet metal components designed to pass current. Interconnects may becompliant (e.g., flexible). A wire may refer to any cord, strip, orelongated electrical conduit. Wires can be flexible. As used herein, abraided metal strip is a wire. In some cases, a busbar is a wire.

In some implementations, interconnections may be configured to decreaseresistance (e.g., internal resistance) in a system (e.g., a battery). Abattery with a low system resistance (e.g., such that the battery iscapable of efficiently storing energy and delivering power) may bedesirable in some cases. The system resistance can be determined by thecombined effect of a plurality of resistances along the current flowpath such as between electrochemical cells, within electrochemicalcells, and between groups of electrochemical cells. In some cases,electrochemical cells or groups thereof are connected usinginterconnects. In some instances, an interconnect is a wire. However,the shortest possible electrical connection can generally lead to thelowest system resistance. Therefore, the present disclosure describesdirect connection of cells to each other (e.g., by brazing), in somecases reducing or eliminating the use of wires to connectelectrochemical cells.

The internal resistance of the battery can be any suitably lowresistance. In some cases, the internal resistance of the battery (e.g.,at the operating temperature) is less than or equal to about 2.5*n*R,where ‘n’ is the number of series connected modules of the battery and‘R’ (also referred to herein as ‘R_(Module)’) is the resistance of eachof the individual modules or parallel connected modules. In someexamples, the inverse of R is the sum of the inverses of the resistanceof each electrochemical cell in a given module, as given by, forexample, 1/R_(Module)=Σ_(i=1) ^(m)1/R_(i), where ‘m’ is the number ofcells in one module. Each module can include a plurality ofelectrochemical cells in a parallel configuration. Electrochemical cellsin adjacent modules can be arranged in a series configuration (e.g.,individual cells in a module can be connected in series withcorresponding individual cells in an adjacent module, such as, forexample, in a configuration where individual cells of a first module areconnected in series with individual cells of a second module locatedabove the first module). In some cases, the internal resistance of thebattery (e.g., at the operating temperature) is less than or equal toabout 2.5*n*R, 2*n*R, 1.5*n*R, 1.25*n*R or 1.05*n*R. In some cases, thetotal system resistance (e.g., at the operating temperature) is greaterthan about 1.0*n*R due to the resistance contribution of interconnects,busbars, surface contact resistance at connection interfaces, etc. Thebattery can comprise electrochemical cells connected in series and inparallel. The number of electrochemical cell modules (or parallelconnected modules) that are connected in series (i.e., n) can be anysuitable number. In some examples, n is at least 3, at least 5, at least6, at least 10, at least 12, at least 15, at least 16, at least 20, atleast 32, at least 48, at least 54, at least 64, at least 108, at least128, at least 216, or at least 256. In an example, n is 3 (e.g., for abattery comprising a pack), 6 (e.g., for a battery comprising a pack),or 216 (e.g., for a battery comprising a core).

A wired or wire-less (e.g., direct metal-to-metal) interconnectionbetween individual electrochemical cells and/or between groups ofelectrochemical cells can have a given internal resistance. In somecases, electrochemical cells are not connected with wires. In someexamples, series connections (e.g., wire-less cell-to-cell connections,or current transfer plate connections) are created with a connectionthat has an internal resistance of less than or equal to about 0.05milli-ohm (mOhm), 0.1 mOhm, 0.5 mOhm, 1 mOhm, 2 mOhm, 5 mOhm, 10 mOhm,50 mOhm, 100 mOhm or 500 mOhm at an operating temperature greater thanabout 250° C. In some instances, the resistance is measured by a directelectrical connection between the conductor of a first electrochemicalcell and the electrically conducting housing of a second cell. In somecases, one or more busbars and/or interconnects can be used to create aconnection between any two groups of cells. In some examples, such aconnection has an internal resistance of less than or equal to about0.01 mOhm, 0.05 mOhm, 0.1 mOhm, 0.2 mOhm, 0.5 mOhm, 1 mOhm, 5 mOhm, 10mOhm, 50 mOhm or 100 mOhm.

In some instances, the resistance is measured by the voltage drop acrossa busbar (and/or interconnect) while current is flowing through thebusbar (and/or interconnect) according to the following formula:R_(busbar)=V/I, where ‘R_(busbar)’ is the resistance of the busbar(and/or interconnect), ‘V’ is the measured voltage drop across thebusbar (and/or interconnect) and ‘I’ is the current flowing through thebusbar (and/or interconnect). Any aspects of the disclosure described inrelation to internal resistance of cell-to-cell connections may equallyapply to connections between groups of cells at least in someconfigurations, and vice versa. Further, any aspects of the disclosuredescribed in relation to internal resistance of series connections mayequally apply to parallel connections at least in some configurations,and vice versa.

In some implementations, an electrochemical energy storage systemcomprises at least a first electrochemical cell adjacent to a secondelectrochemical cell. Each of the first and second electrochemical cellscan comprise a negative current collector, negative electrode,electrolyte, positive electrode and a positive currently collector. Atleast one of the negative electrode, electrolyte and positive electrodecan be in a liquid state at an operating temperature of the first orsecond electrochemical cell. A positive current collector of the firstelectrochemical cell can be direct metal-to-metal joined (e.g., brazedor welded) to the negative current collector of the secondelectrochemical cell. In some examples, the negative current collectorcomprises a negative current lead.

In some cases, the first and second electrochemical cells are notconnected by wires. In some cases, the electrochemical energy storagesystem comprises one or fewer interconnects for every 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30 or more electrochemical cells. In some cases, theelectrochemical energy storage system (e.g., battery) comprises oneinterconnect for at least every 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20,25, 30, 40, 50, 75, 100, 150, 200, or more electrochemical cells.

FIG. 28 shows an example of a cell pack 2800 comprising 3 modules 2805.Each of the modules comprises 12 cells 2830 that are connected inparallel 2810. The modules are held in place with cell pack framing(also “frame” herein) 2815 that includes a top component of the frame2820. The cells are stacked directly on top of each other with thenegative current terminal of one cell 2825 contacted directly with thehousing of another cell (e.g., the cell above it). The negative currentterminals of the top layer of cells will have no housing of another celldirectly above, so can instead be contacted (e.g., brazed to) a negativebusbar 2835.

In some configurations, the parallel connections 2810 made in the modulecan be created using a single piece (or component) with multiple pocketsfor cell materials. This piece can be a stamped component that allowsfor direct electrical connection between cells. In some examples, thestamped pocketed electrically conductive housing does not create abarrier between the cells. In some cases, the pocketed electricallyconductive housing seals the pockets from each other. This electricallyconductive housing can be easier to manufacture and assemble thanindividual electrically conductive cell housings. In someconfigurations, the parallel connections 2810 made in the module can becreated by direct contact of the housings of the cells in the module.

When stacked vertically, the electrochemical cells bear the weight ofthe cells stacked above. The cells can be constructed to support thisweight. In some cases, cell-to-cell spacers 640 are placed between thelayers of cells. These spacers can disperse the weight of the abovecells and/or relieve some of the weight applied to the negative currentterminals. In some cases, the negative current terminals areelectrically isolated from the housing with a seal. This seal can be theweakest structural component of the electrochemical cell, so the spacerscan reduce the amount of force applied to the seals.

In some implementations, a liquid metal battery comprises a plurality ofelectrochemical cells each comprising an electrically conductive housingand a conductor in electrical communication with a current collector.The electrically conductive housing can comprise a negative electrode,electrolyte and positive electrode that are in a liquid state at anoperating temperature of the cell. The conductor can protrude throughthe electrically conductive housing through an aperture in theelectrically conductive housing and can be electrically isolated fromthe electrically conductive housing with a seal. The plurality ofelectrochemical cells can be stacked in series with the conductor of afirst cell in electrical contact with the electrically conductivehousing of a second cell. The liquid metal battery can also comprise aplurality of non-gaseous spacers disposed between the electrochemicalcells. In some cases, the electrochemical cells are stacked vertically.For example, at least 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 36,40, 48, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 216, 250, 256,300, 350, 400, 450, 500, 750, 1000, 1500, 2000 or more electrochemicalcells can be stacked in series. In some cases, the battery furthercomprises at least one additional electrochemical cell connected inparallel to each of the plurality of electrochemical cells that arestacked in series. For example, each vertically stacked cell can beconnected in parallel with at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15,16, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200,250, 300, 350, 400, 450, 500, 750, 1000, 1500, 2000 or more additionalelectrochemical cells. In some cases, the electrically conductivehousings are part of a current conducting pathway.

The non-gaseous spacers (also “spacers” herein) can be a solid material.In some cases, the spacers comprise a ceramic material. Non-limitingexamples of ceramic materials include aluminum nitride (AlN), boronnitride (BN), yttrium oxide (Y₂O₃), zirconium oxide (ZrO₂), yttriapartially stabilized zirconia (YPSZ), aluminum oxide (Al₂O₃),chalcogenides, erbium oxide (Er₂O₃), silicon dioxide (SiO₂), quartz,glass, or any combination thereof. In some cases, the spacers areelectrically insulating.

The spacers can have any suitable thickness. In some cases, thethickness of the spacer is approximately equal to the distance that theconductor protrudes out of the electrically conductive housing (e.g.,the thickness of the spacer can be within less than or equal to about0.005%, 0.01%, 0.05%, 0.1% or 0.5% of the distance that the conductorprotrudes out of the electrically conductive housing).

The majority of the force (e.g., the weight of electrochemical cellsstacked vertically above a cell) is generally born by the spacers and/orhousing rather than the seals. The non-gaseous spacers and/or theelectrically conductive housing can support any suitably high percentageof the applied force. In some cases, greater than or equal to about 70%,80%, 90% or 95% of the force is applied to the non-gaseous spacersand/or the electrically conductive housing.

There can be any suitable amount of force applied to the electricallyconductive housing and/or seal. In some instances, the force applied tothe seal is no greater than the seal can support. In some cases, theforce applied to the seal is less than or equal to about 10, 15, 20, 25,30, 35, 40, 45, 50, 60, 70, 80, 100, 120, 150 or 200 Newtons (N). Insome cases, the force applied to the housing is greater than or equal toabout 100, 500, 1,000, 5,000 or 10,000 N.

There can be any suitable amount of pressure applied to the electricallyconductive housing and/or seal. In some instances, the pressure appliedto the seal is no greater than the seal can support. In some cases, thepressure applied to the seal is less than or equal to about 1, 10, 50,100, 200, 300 or 500 pounds per square inch (psi). In some cases, thepressure applied to the housing is greater than or equal to about 500,1,000, 2,000, 2,500, 3,000, 5,000 or 10,000 psi.

The cell to cell connections can be configured in a variety of waysbased on tolerances and optimal conductive path. In one configuration,the top face of the negative current lead in one cell can be directmetal-to-metal joined (e.g., brazed, welded) to the bottom of the cellabove it (see, for example, FIG. 29). Other configurations can include,for example, alternative direct metal-to-metal joined (e.g., alternativebraze joined) configurations, such as an outer diameter braze enhancedby differences in the coefficient of thermal expansion (CTE) of theinner rod and the outer fixture (see, for example, FIG. 30). of thermalexpansion (CTE) of the inner rod and the outer fixture (FIG. 30).

In some cases, as shown in FIG. 29, the conductor 2905 of a first cell2910 is brazed 2915 to the electrically conductive housing 2920 of thesecond cell 2925. The braze material can be any suitable material. Somenon-limiting examples of braze materials include materials that compriseiron (Fe), nickel (Ni), titanium (Ti), chromium (Cr), zirconium (Zr),phosphorus (P), boron (B), carbon (C), silicon (Si), or any combinationthereof. The cell can comprise a cathode 2930, an electrolyte 2935 andan anode 2940 connected to the current collector and conductor 2905. Theconductor can feed through the cell lid 2950. In some cases, the cellhas some empty head space 2945.

In some implementations, the conductor 2905 can feed through a seal 2960in the cell lid 2950. The conductor (e.g., negative current lead) 2905may rigid. The seal 2960 may not be rigid. As additional cells are addedduring assembly, an increasing weight can be exerted on the conductor2905 of the bottom cell 2910 by the housing 2920 of the top cell 2925(e.g., at the position 2915). In some instances, the vertical spacingbetween the cells 2910 and 2925 may decrease if the seal 2960 (with theconductor 2905 and the anode 2940) move downward into the cell 2910 as aresult of the compression force. To ensure that modules are electricallyisolated from each other, spacers (e.g., ceramics) 2955 can be placedacross the surface of the cells to support the cells above them. In thisconfiguration, the cell housing can be used as the main structuralsupport for the system. The ceramic spacer 2955 can relieve the seal2960 from having to support the weight of the top cell 2925 (and anyadditional cells added during assembly). In some configurations, theremay initially be a gap between the top of the spacers 2955 and thebottom of the housing 2920 of the top cell 2925 (e.g., the thickness ofthe spacer can be slightly less than the distance that the conductorinitially protrudes through the electrically conductive housing), andthe spacers (e.g., ceramics) can be placed in compression duringassembly as additional cell(s) are added (e.g., as the spacing betweenthe top of the housing of the bottom cell 2910 and the bottom of thehousing of the top cell 2925 decreases). As a result, the displacement(also “anode-cathode displacement” herein) between anodes and cathodes(e.g., final displacement after assembly between the anode 2940 and thecathode 2930 in cell 2910) can in some cases be determined by thenon-gaseous spacers. In some configurations, the spacers can be placedin compression right away (e.g., if the thickness of the spacer isslightly greater than the distance that the conductor initiallyprotrudes through the electrically conductive housing).

In some cases, differences in the coefficient of thermal expansion (CTE)can be used to connect two cells. As shown in FIG. 30, the conductor ofthe first cell 3005 sits in a recessed portion of the electricallyconductive housing of the second cell 3010, and the coefficient ofthermal expansion (CTE) of the conductor 3015 is greater than the CTE ofthe electrically conductive housing 3020.

The CTE of the conductor can be any amount greater than the CTE of theelectrically conductive housing. In some cases, the CTE of the conductoris greater than or equal to about 2%, 5%, 10%, 15%, 20%, 30%, 40%, 50%,60%, 70%, 80%, 90% or 100% greater than the CTE of the electricallyconductive housing.

Cells stacked vertically in series can be attached through a direct orhard electrical connection such that the height from 2950 to 2940 and/oranode-cathode displacement (ACD) can be determined by the dimensionaltolerance of 2955. In some examples, the height from 2950 to 2940 can beat least about 3 millimeters (mm), 5 mm, 7 mm, 10 mm, 15 mm, and thelike. In some examples, the ACD can be at least about 3 mm, 5 mm, 7 mm,10 mm, 15 mm or greater. FIG. 29 is an example of how such connectionsmay be configured.

Cells stacked vertically in series can be connected using a direct(e.g., metal-to-metal) electrical connection such that resistance percell connection is reduced, for example, below about 100 mOhm (oranother internal resistance value described elsewhere herein). FIG. 29is an example of how such connections may be configured. FIG. 29 alsoprovides an example of a CTE mismatched seal connection.

In some implementations, cells can be joined vertically using a currenttransfer plate that can be connected (e.g., welded) to the negativecurrent lead or conductor on the bottom cell, and the cell body (e.g.,electrically conductive housing) on the top cell. The negative currentlead can protrude through a housing of the bottom cell through a seal.For example, multiple cells can be connected in parallel into a cellmodule or a partial cell module, and then connected in series with othercell modules or partial cell modules via vertical stacking. The verticalstacking can be implemented by connecting the current transfer platefrom one cell to the cell body or a feature on the cell body on the cellabove it (e.g., to form the basis of a cell pack). The current transferplate can be formed from a conductive material, such as any conductivematerial described herein. The current can comprise one or more surfaces(e.g., a flat surface) that can be welded or otherwise directmetal-to-metal joined with another surface (e.g., a cell body or afeature on the cell body of an adjacent cell). The current transferplate can extend from the negative current lead toward the periphery ofthe cell surface comprising the negative current lead. Suchconfigurations can enable electrical connections to be more convenientlymade in tight spaces between cells or in cell assemblies (e.g., moreconvenient access during vertical stacking of cells).

The current transfer plate may be combined with or comprise a strainrelieving function to reduce stress on the seal (e.g., the seal aroundthe negative current lead) that may be generated by the welding/joiningprocess and/or thermal expansion differences during heat-up and/orcool-down, and/or stresses generated when cells and/or packs arevertically stacked on top one another. In some cases, the stresses onthe seal may be reduced by including an electrically insulatingnon-gaseous (e.g., ceramic) spacer. The non-gaseous spacer can supportthe weight from the current transfer plate and/or cells stacked onto thecurrent transfer plate and direct the weight onto the housing (e.g., thecell cap), thereby reducing the portion of the applied weight that istransmitted through the seal. In some cases, the strain relievingfunction may include a spiral pattern (e.g., a single spiral arm ormultiple spiral arms) or other feature on the current transfer plate togive the current transfer plate compliance and may reduce stressexperienced by the seal as the cells are stacked on top one another orduring heat-up due to CTE mismatches. The spiral pattern may compriseone or more spiral arms. The spiral arms may be, for example, less thanor equal to about 0.5 mm, 1 mm, 2 mm or 4 mm thick. The spiral arms maycreate a spiral that has a circular or oval external shape that isgreater than or equal to about 1 cm, 2 cm, 3 cm or 4 cm or larger indiameter. In some cases, the current transfer plate may be sufficientlycompliant such that the strain relieving feature is not needed.

Cell packs can be attached in series and parallel in variousconfigurations to produce cores, CEs, or systems. The number andarrangement of various groups of electrochemical cells can be chosen tocreate the desired system voltage and energy storage capacity. Thepacks, cores, CEs, or systems can then be enclosed together in hightemperature insulation to create a system that can heat itself using theenergy created from cells charging and discharging. For example, FIG. 31is an example of how packs can be configured, indicating that the cellpacks in a given plane are connected to one another in parallel 3105,while the packs connected directly atop one another are connected inseries 3110.

The packs themselves can be connected vertically and horizontally to oneanother through busbars (e.g., unlike the cell-to-cell connectionswithin a pack which can generally be direct connections such as brazesor welds). In some cases, the busbar is flexible or comprises a flexiblesection (e.g., to accommodate non-isothermal expansion of the systemthroughout heat up and operation).

A busbar can be used to make an electrical connection with cells in aparallel string (e.g., a parallel string of cells, a parallel string ofpacks, etc.). In some examples, a busbar can be used to configure a setof cells or cell modules into a parallel string configuration by beingelectrically connected with the same terminal on all of the cells orcell modules (e.g., the negative terminals of all of the cells or cellmodules, or the positive terminals of all of the cell or cell modules).For example, a positive busbar and/or a negative busbar may be used. Thepositive busbar can be connected to the housing and may or may not needto be flexible. In some cases, the positive busbar may not be used. Thenegative busbar can be joined to features in (or on) one or more of thecell bodies (e.g., the cell bodies of individual cells in a pack) toprovide a strong electrical connection. In some cases, the negativebusbar can be attached to conductive feed-throughs (e.g., negativecurrent leads), which may require some compliance for thermal expansion.For example, a flexible connection between a relatively rigid busbarcore and the feed-through may be achieved using a compliance featurebetween the feed-through and the busbar. The compliance feature mayinvolve a spiral pattern (e.g., a single spiral arm or multiple spiralarms) that may be created by cutting away and/or removing material froma flat busbar in the desired pattern. The spiral pattern may compriseone or more spiral arms. The spiral arms may be, for example, less thanor equal to about 0.5 mm, 1 mm, 2 mm or 4 mm thick. The spiral arms maycreate a spiral that has a circular or oval external shape that isgreater than or equal to about 1 cm, 2 cm, 3 cm or 4 cm or larger indiameter. In some cases, the busbar may be sufficiently compliant suchthat the compliance feature is not needed.

One or more interconnects can be used to connect the busbar of one packto the busbar of another cell pack, thereby placing the cell packs inparallel or in series. In some cases, the negative busbar of one cellpack is connected to the positive busbar of another cell pack using acompliant interconnection component (also “interconnect” herein). Insome cases, the interconnect may be braided metal or metal alloy. Insome cases, the interconnect may be made from sheet metal and take theform of a bent sheet that is less than or equal to about 1/32 inch, 1/16inch, ⅛ inch or ¼ inch thick. In some cases, the interconnect maycomprise the same conductive material as the busbar. In some cases, thepositive busbar and the interconnect are the same component.

The busbar and/or interconnect components can comprise a conductivematerial. For example, the busbar and/or interconnect components cancomprise (e.g., be made of) stainless steel, nickel, copper,aluminum-copper based alloy, or any combination thereof.

The pack may further comprise or form other interconnections (e.g., toallow the pack to be interconnected with additional packs), including,but not limited to, additional interconnects, additional busbars and/oradditional connection interfaces. In some implementations, busbars maybe used to provide pack-level electrical connections/interconnections(e.g., only busbars may be used for pack-level electricalconnections/interconnections).

In configurations where cells are stacked vertically atop one another,the busbar at the top of the cell stack (e.g., cell pack stack) cancomprise only the negative busbar (e.g., since the positive terminal ofthe stack can be on the bottom cell in the stack).

The thermal insulation and/or the frame may be designed to allow thecore (and/or any system of the disclosure) to be cooled, the insulationto be removed, individual or sets of packs to be disconnected andremoved from the core to allow for a single pack to be disconnected,removed and replaced, or any combination thereof. The core can then bereassembled and heated back up to operating temperature to allow forresumed operation.

Various interconnection configurations described herein in relation toindividual cells or a given group of cells may equally apply to othergroups of cells (or portions thereof) at least in some configurations.In one example, interconnections such as, for example, brazed positiveand negative current collectors of cells, braze enhanced by differencesin coefficients of thermal expansion, connecting (e.g., welding) cellbodies or features in cell bodies, etc., may apply to (or be adapted to)groups of cells such as, for example, modules, packs, etc. In anotherexample, interconnections such as, for example, stamped pocketedelectrically conductive housing in cells and/or modules, etc., may applyto (or be adapted to) groups of cells such as, for example, modules,packs, etc. In yet another example, interconnections such as, forexample, busbars/interconnects between packs, etc., may in some casesapply to (or be adapted to) groups of cells such as, for example, cores,etc. Further, stress-relieving configurations (e.g., current transferplates between cells, spacers, spiral relief or compliancefeatures/structures/patterns, etc.) and electrical/structural features(e.g., end-caps, etc.) may in some cases be applied to (or be adaptedto) any group of cells herein. The various interconnectionconfigurations may be applied at group level or to individual cells.Thus, in an example, a spacer used between cells may be configured foruse as a spacer between packs, a current transfer plate between cellsmay be configured for use between modules, an interconnection interfacecomprising a feature on a cell body for connecting cell bodies within amodule may be configured for connecting cell bodies of outer cells onadjacent packs, and so on. Further, interconnections described inrelation to forming a series connection may be in some cases be adaptedto forming a parallel connection, and vice versa.

Devices, systems and methods of the present disclosure may be combinedwith or modified by other devices, systems and/or methods, such as, forexample, batteries and battery components described in U.S. Pat. No.3,663,295 (“STORAGE BATTERY ELECTROLYTE”), U.S. Pat. No. 3,775,181(“LITHIUM STORAGE CELLS WITH A FUSED ELECTROLYTE”), U.S. Pat. No.8,268,471 (“HIGH-AMPERAGE ENERGY STORAGE DEVICE WITH LIQUID METALNEGATIVE ELECTRODE AND METHODS”), U.S. Patent Publication No.2011/0014503 (“ALKALINE EARTH METAL ION BATTERY”), U.S. PatentPublication No. 2011/0014505 (“LIQUID ELECTRODE BATTERY”), U.S. PatentPublication No. 2012/0104990 (“ALKALI METAL ION BATTERY WITH BIMETALLICELECTRODE”), and U.S. Patent Publication No. 2014/0099522(“LOW-TEMPERATURE LIQUID METAL BATTERIES FOR GRID-SCALED STORAGE”), eachof which is entirely incorporated herein by reference.

Energy storage devices of the disclosure may be used in grid-scalesettings or stand-alone settings. Energy storage device of thedisclosure can, in some cases, be used to power vehicles, such asscooters, motorcycles, cars, trucks, trains, helicopters, airplanes, andother mechanical devices, such as robots.

EXAMPLES Example 1: Materials of Construction

Alloys of tungsten (W) and molybdenum (Mo), such as, for example, thoselisted in TABLE 3, can be used in the seals of the disclosure. Thealloys can be used as the component (e.g., W or Mo) that is brazed tothe electrically insulating ceramic (e.g., aluminum nitride). In somecases, the tungsten and/or molybdenum alloy has a coefficient of thermalexpansion (CTE) that is matched with the ceramic (e.g., within less thanor equal to about 1%, 5% or 10% of the CTE of the ceramic), issubstantially resistant to oxidation, and/or is substantially resistantto attack, alloying and/or corrosion from the metal vapor of thenegative electrode (e.g., lithium, sodium, potassium, magnesium orcalcium vapor) or the molten salt.

TABLE 3 EXAMPLES OF TUNGSTEN AND MOLYBDENUM ALLOYS Material BrandDescription Composition Mo Mo Molybdenum 99.97% Mo TZM TZMTitanium-Zirconium-Molybdenum 0.5% Ti/0.08% Zr/ 0.01-0.04% C MHC MHCMolybdenum-Hafnium-Carbon 1.2% Hf/0.05-0.12% C Mo- MLMolybdenum-Lanthanum Oxide 0.3% La₂O₃-0.7% La₂O₃ Lanthanoxid (ML) Mo-MLR (R = Molybdenum-Lanthanum Oxide 0.7% La₂O₃ LanthanoxidRecrystallized) (ML) Mo- MLS (S = Molybdenum-Lanthanum Oxide 0.7% La₂O₃Lanthanoxid Stress (ML) relieved) MoILQ MoILQ (ILQ = Molybdenum-ILQ0.03% La₂O₃ Incandescent Lamp Quality) Mo- MY Molybdenum-Yttrium-Cerium0.47% Y₂O₃/ Yttriumoxid Oxide 0.08% Ce₂O₃ MoRe MoRe5 Molybdenum-Rhenium5.0% Re MoRe MoRe41 Molybdenum-Rhenium 41.0% Re MoW MW20Molybdenum-Tungsten 20.0% W MoW MW30 Molybdenum-Tungsten 30.0% W MoWMW50 Molybdenum-Tungsten 50.0% W MoCu MoCu30 Molybdenum-Copper 30.0% CuMoCu MoCu15 Molybdenum-Copper 15.0% Cu MoZrO2 MZ17 Molybdenum-Zirconium1.7% ZrO₂ Oxide MoTa MT11 Molybdenum-Tantalum 11.0% Ta MoNb MoNbMolybdenum-Niobium W (pure) W (pure) Tungsten >99.97 W-NS W-NSTungsten-Non Sag 60-65 ppm K WVM WVM Tungsten Vacuum 30-70 ppm KMetallizing WVMW WVMW WVM-Tungsten 15-40 ppm K S-WVMW S-WVMWS-WVM-Tungsten 15-40 ppm K WC WC20 Tungsten Cerium Oxide 2.0% CeO₂ WLWL10 Tungten-Lanthanum Oxide 1.0% La₂O₃ WL WL15 Tungten-Lanthanum Oxide1.5% La₂O₃ WL WL20 Tungten-Lanthanum Oxide 2.0% La₂O₃ WL-S WL-STungsten-Lanthanum 1.0% La₂O₃ Oxide-Stem WLZ WLZ Tungsten-Lanthanum 2.5%La₂O₃/ Oxide-Zirconium Oxide 0.07% ZrO₂ WT WT20 Tungsten-Thorium Oxide2.0% ThO₂ WT WVMT10 Tungsten-Thorium Oxide 30-70 ppm K/ 1.0% ThO₂ WTWVMWT Tungsten-Thorium Oxide 5-30 ppm K/ 2.0% ThO2 WRe WRe5Tungsten-Rhenium 5.0% Re WRe WRe26 Tungsten-Rhenium 26.0% Re WCu WCuTungsten-Copper 10-40% Cu W-High- DENSIMET ® DENSIMET ® 1.5%-10% Ni, Fe,density Mo tungsten- heavy metal alloys W-High- INERMET ® INERMET ®5%-9.8% Ni, Cu density tungsten- heavy metal alloys W-High- DENAL ®DENAL ® 2.5%-10% Ni, Fe, density Co tungsten- heavy metal alloys

It is to be understood that the terminology used herein is used for thepurpose of describing specific embodiments, and is not intended to limitthe scope of the present invention. It should be noted that as usedherein, the singular forms of “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. In addition,unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. An electrochemical cell, comprising: a containercomprising a conductor aperture, wherein said container is configured tocontain a reactive material at a temperature of at least about 200° C.;a conductor that extends from an environment external to said containerthrough said conductor aperture into said container; and a sealing unitthat couples said container to said conductor to seal said conductoraperture, wherein said sealing unit comprises a ceramic componentcoupled to said container and said conductor, wherein said ceramiccomponent is configured to be exposed to said reactive material whilesealing said conductor aperture, and wherein said ceramic componentcomprises a grain size that is less than or equal to about 50micrometers (μm).
 2. The electrochemical cell of claim 1, wherein saidgrain size is less than or equal to about 10 μm.
 3. The electrochemicalcell of claim 1, wherein said ceramic component has a porosity of lessthan or equal to about 3% by volume.
 4. The electrochemical cell ofclaim 1, wherein said ceramic component is a ring, and wherein said ringis disposed around said conductor.
 5. The electrochemical cell of claim1, wherein said ceramic component has one or more beveled edges.
 6. Theelectrochemical cell of claim 1, wherein said sealing unit furthercomprises a metal sleeve configured to couple said ceramic component tosaid container or to said conductor.
 7. The electrochemical cell ofclaim 6, wherein said metal sleeve comprises a material selected fromthe group consisting of grade 304 stainless steel, grade 430 stainlesssteel, 410 stainless steel, zirconium, an iron-nickel alloy, and 18CrCbferritic stainless steel.
 8. The electrochemical cell of claim 6,wherein said metal sleeve has a thickness of greater than or equal toabout 75 μm.
 9. The electrochemical cell of claim 8, wherein saidthickness is less than or equal to about 250 μm.
 10. The electrochemicalcell of claim 6, wherein said metal sleeve is coupled to said ceramiccomponent, said container, or said conductor by a braze.
 11. Theelectrochemical cell of claim 10, wherein said braze comprises one ormore member selected from the group consisting of silver, aluminum,titanium, nickel, and combinations thereof.
 12. The electrochemical cellof claim 11, wherein said braze comprises silver and less than or equalto about 5% aluminum.
 13. The electrochemical cell of claim 11, whereinsaid braze comprises titanium and one or more members selected from thegroup consisting of zirconium, copper, and nickel.
 14. Theelectrochemical cell of claim 1, wherein said ceramic componentcomprises aluminum nitride.
 15. The electrochemical cell of claim 14,wherein said ceramic component further comprises less than or equal toabout 5% yttrium oxide.
 16. The electrochemical cell of claim 1, whereinsaid reactive material comprises a molten metal and a molten salt. 17.The electrochemical cell of claim 16, wherein said molten metalcomprises magnesium, calcium, sodium, barium, potassium, lithium, or anycombination thereof.
 18. The electrochemical cell of claim 1, whereinsaid ceramic component is unreactive to said reactive material or vaporsof said reactive material.